Root RAID HOWTO cookbook

Root RAID HOWTO cookbook
Michael A. Robinton, [email protected]
<mailto:[email protected]>
v1.12, May 2, 2000

This document only applys to the OLD raidtools, versions 0.50 and
under. The workarounds and solutions addressed in this write up have
largely been made obsolete by the vast improvment in the 0.90 raid�
tools and accompanying kernel patch to the 2.0.37, 2.2x and 2.3x
series kernels. You may find the detailed descriptions useful, partic�
ularly if you plan to run root raid or use initrd. Read on for a ref�
erence to set up of Boot Root Raid using conventional LILO and accom�
panying initrd working scripts. What follows is the description of the
now OBSOLETE Root RAID HOWTO. This document was originally written to
provide a cookbook for creating a root mounted raid filesystem and
companion fallback rescue system using linux initrd. There are com�
plete step-by-step instruction for both raid1 and raid5 md0 devices.
Each step is accompanied by an explanation of it's purpose. Included
with this revision is a generic linuxrc initrd file which may be con�
figured with a single three line ``/etc/raidboot.conf'' file for raid1
and raid5 configurations.
______________________________________________________________________

Table of Contents

1. Introduction

1.1 Where to get Up-to-date copies of this document.
1.2 More up-to-date Boot Root Raid with LILO minihowto
1.3 Bugs
1.4 Acknowledgements
1.5 Copyright Notice

2. What you need BEFORE YOU START

2.1 Required Packages
2.2 Other similar implementations.
2.3 Documentation -- Recommended Reading
2.4 RAID resources

3. Quick Start for ROOT RAID

4. (IT

4.1 Security Reminder
4.2 Build the Kernel and Raid Tools
4.3 Build the
4.4 Start the STEP by STEP instructions
4.5 Install the distribution - Slackware Specific
4.6 Install linux
4.7 Install Raid Tools
4.8 Remove un-needed directories and files from new filesystem.
4.9 Create /dev/md
4.10 Create a bare filesystem suitable for
4.10.1 Create the BOOT/RESCUE
4.10.2 Corrections for the Rescue System
4.11 Making 'initrd' boot the RAID device - linuxrc
4.12 Modifying the rc-scripts for SHUTDOWN
4.13 Configuring RAIDBOOT - raidboot.conf
4.14 Kernel 'loadlin and lilo' variables for RESCUE and RAID

5. Configuring the Production RAID system.

5.1 System specs. Two systems with identical motherboards were configured.
5.2 Partitioning the hard drives.

6. Building the RAID file system.

6.1 /etc/raid5.conf
6.2 /etc/raid1.conf
6.3 Step by Step procedures for building production RAID file system.

7. One last thought.

8. Appendix A. - Bohumil Chalupa's md0 shutdown

9. Appendix B. - Sample SHUTDOWN scripts

9.1 Slackware - /etc/rc.d/rc.6
9.2 Debian bo - /etc/init.d/halt and /etc/init.d/reboot
9.2.1 /etc/init.d/halt
9.2.2 /etc/init.d/reboot

10. Appendix C. - other setup files

10.1 linuxrc
10.2 loadlin -- linux.bat file - boot.par
10.3 linuxthreads Makefile.diff
10.4 raid1.conf
10.5 raid5.conf
10.6 raidboot.conf
10.7 rc.raidown

11. Appendix D. - obsolete linuxrc and shutdown scripts

11.1 Obsolete working - linuxrc
11.2 Obsolete working - shutdown scripts

12. Appendix E. - Gadi's raid stop patch for the linux kernel

13. Appendix F. - rc.raidown

14. Appendix G. - linuxrc theory of operation

15. Appendix H. Setting up ROOT RAID on RedHat

______________________________________________________________________

1. Introduction

The reader is assumed to be familiar with the various types of raid
implementations, their advantages and drawbacks. This is not a
tutorial, just a set of instructions on how to implement root mounted
raid on a linux system. All of the information necessary to become
familiar with linux raid is listed here directly or by reference,
please read it before send e-mail questions.

1.1. Where to get Up-to-date copies of this document.

Click here to browse the author's latest version
<ftp://ftp.bizsystems.com/pub/raid/Root-RAID-HOWTO.html> of this
document. Corrections and suggestions welcome!

Root-RAID-HOWTO -- OBSOLETE

Available in LaTeX (for DVI and PostScript), plain text, and HTML.

http://www.linuxdoc.org/HOWTO/Root-RAID-HOWTO.html
<http://www.linuxdoc.org/HOWTO/Root-RAID-HOWTO.html>

Available in SGML and HTML.

ftp.bizsystems.net/pub/raid/ <ftp://ftp.bizsys�
tems.net/pub/raid/>

1.2. More up-to-date Boot Root Raid with LILO minihowto

Available in LaTeX (for DVI and PostScript), plain text, and HTML.

http://www.linuxdoc.org/HOWTO/Root-RAID-HOWTO.html
<http://www.linuxdoc.org/HOWTO/Root-RAID-HOWTO.html>

Available in SGML and HTML.

ftp.bizsystems.net/pub/raid/ <ftp://ftp.bizsys�
tems.net/pub/raid/>

1.3. Bugs

As of this writing, the problem of stopping a root mounted RAID device
has not yet been solved in a satisfactory way. A work-around proposed
by Ed Welbon and implemented by Bohumil Chalupa is incorporated into
this document which eliminates the need for a long ckraid at each boot
for raid1 and raid5 devices. Without the workaround, it is necessary
to ckraid the md device each time the system is re-booted. On a large
array this can cause a severe availability performance degradation.
On my 6 gig RAID1 device running on a Pentium 166 with 128 megs of
ram, it takes well over half an hour to ckraid :-( after each re-boot.
It takes over an hour on my 13 gig RAID5 array with a 20mb/sec scsi
adaptor.

The workaround stores the status of the array at shutdown on the real
boot device and compares it to a reference status placed there when
the system is first built. If the status's match at reboot, the
superblock on the array is rebuilt on the next boot, otherwise the
operator is notified of the status error and the rescue system is left
running with all the raid tools available.

Rebuilding the superblock causes the system to ignore that the array
was powered down without mdstop by marking all the drives as OK, as if
nothing happened. This only works if all the drives are OK at
shutdown. If the array was operating with a bad drive, the operator
must remove the bad drive prior to restarting the md device or the
data can be corrupted.

None of this applies to raid0 which does not have to be mdstopped
before shutdown.

Final proposed solutions to this problem include a finalrd similar to
initrd, and mdrootstop which writes the clean flags to the array
during shutdown when it is mounted read only. I am sure there are
others.

In the mean time, the problem has been by-passed for now Please let me
know when this problem is solved more cleanly!!!

1.4. Acknowledgements

The writings and e-mail from the following individuals helped to make
this document possible. Many of the ideas were stolen from the
helpful work of others, I have just tried to put it all in COOKBOOK
form so that it is straightforward to use. My thanks to:

� Linas Vepstas <mailto:[email protected]>
for the RAID howto that explained most of this to me.

� Gadi Oxman <mailto:[email protected]>
for answering my dumb 'newbie' questions.

� Ed Welbon <mailto:[email protected]>
for the execellent initrd.md package that inspired me to write
this.

� Bohumil Chalupa <mailto:[email protected]> for
implementing the re-boot 'workaround' that allows root-mounted-raid
to work in a production environment.

� Keith W. <mailto:[email protected]> for his explaination of
setting up root raid with RedHat.

� and many others who contributed to this work in one way or another.

1.5. Copyright Notice

This document is GNU copyleft by Michael Robinton [email protected]
<mailto:[email protected]>.

Permission to use, copy, distribute this document for any purpose is
hereby granted, provided that the author's / editor's name and this
notice appear in all copies and/or supporting documents; and that an
unmodified version of this document is made freely available. This
document is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY, either expressed or implied. While every effort
has been taken to ensure the accuracy of the information documented
herein, the author / editor / maintainer assumes NO RESPONSIBILITY for
any errors, or for any damages, direct or consequential, as a result
of the use of the information documented herein.

2. What you need BEFORE YOU START

The packages you need and the documentation that answers the most
common questions about setting up and running raid are listed below.
Please review them throughly.

2.1. Required Packages

You need to obtain the most recent versions of these packages.

� a linux kernel that supports raid, initrd and /dev/loopx

I used linux-2.0.33 <ftp://sunsite.unc.edu/pub/Linux/ker�
nel/> from sunsite

� raid145-971022-2.0.31
<ftp://ftp.kernel.org/pub/linux/daemons/raid/> patch adds support
for raid1/4/5

� raidtools-pre3-0.42 <ftp://ftp.kernel.org/pub/linux/daemons/raid/>
tools to create and maintain raid devices (documentation too).

� ``Gadi's raid stop patch'' in Appendix E.

� linuxthreads-0.71
<ftp://ftp.inria.fr/INRIA/Projects/cristal/Xavier.Leroy> required
threads package. Use ftp, browser doesn't work
ftp.inria.fr/INRIA/Projects/cristal/Xavier.Leroy

� A Linux distribution, ready to install.

I used Slackware-3.4 <ftp://ftp.cdrom.com/pub/linux>

Helpful but not required

� raidboot-0.01.tar.gz <ftp://ftp.bizsystems.com/pub/raid/> pre-built
raid rescue/boot system.

The detailed instructions in this document are based on the above
packages. If the packages have been updated or you use a different
linux distribution, you may have to modify the procedures you find
here.

The patches, tool assortment, etc... may vary with 2.1 kernels.
Please check the most recent documentation at:

ftp.kernel.org/pub/linux/daemons/raid/ <ftp://ftp.ker�
nel.org/pub/linux/daemons/raid/>

2.2. Other similar implementations.

I chose to include in the kernel all of the pieces necessary to run
from boot without loading any modules. My kernel image is a little
over 300k compressed.

Take a look at Ed Welbon's <mailto:[email protected]> initrd.md.tar.gz
for another way to make a bootable raid device. He uses loadable
modules. A look at his concise scripts will show you how it is done
if you need a very small kernel with modules.

http://www.realtime.net/~welbon/initrd.md.tar.gz
<http://www.realtime.net/~welbon/initrd.md.tar.gz>

2.3. Documentation -- Recommended Reading

Please read:

/usr/src/linux/Documentation/initrd.txt

as well as the documentation and man pages that accompany the
raidtools set. In particular, read man mdadd as well as the
QuickStart.RAID document included in the raidtools package.

You may also wish to review:

� BootPrompt-HOWTO <http://sunsite.unc.edu/mdw/HOWTO/BootPrompt-
HOWTO.html>

� man lilo

� man lilo.conf

2.4. RAID resources

� www.linas.org/linux/Software-RAID/Software-RAID.html
<http://http://www.linas.org/linux/Software-RAID/Software-
RAID.html>

� www.ssc.com/lg/issue17/raid.html
<http://www.ssc.com/lg/issue17/raid.html>

� linas.org/linux/raid.html <http://linas.org/linux/raid.html>

� ftp.kernel.org/pub/linux/daemons/raid/
<ftp://ftp.kernel.org/pub/linux/daemons/raid/>

� www.realtime.net/~welbon/initrd.md.tar.gz
<http://www.realtime.net/~welbon/initrd.md.tar.gz>
� luthien.nuclecu.unam.mx/~miguel/raid/
<http://luthien.nuclecu.unam.mx/~miguel/raid/>

Mailing lists can be joined at:

� [email protected] <mailto:[email protected]> send a
message to subscribe raiddev

send mail to: [email protected]
<mailto:[email protected]>

� [email protected] <mailto:[email protected]> send
a message to subscribe linux-raid

send mail to: [email protected] <mailto:linux-
[email protected]> (this seems to be the most active list)

3. Quick Start for ROOT RAID

If you use RedHat, see the ``Howto set up RedHat'' section in Appendix
H. I have not tried this. If you use it successfully, please let me
know so I can update this document.

If you don't want to try and build and debug the rescue system, you
can get a generic one created from Slackware-3.4 from:

ftp.bizsystems.com/pub/raid/raidboot-0.01.tar.gz
<ftp://ftp.bizsystems.com/pub/raid/>

Perform the following steps:

� Compile the raid enabled kernel with built in support for your disk
subsystem

� Test that the raid array will configure and mount correctly

� Build your OS on the raid system

� Correct the entries in fstab to show /dev/md0 as the root device.
Make sure that the partition(s) you use for booting are included in
fstab.

� Modify your shutdown halt and reboot script(s) (mine is
/etc/rc.d/rc.6) as shown in ``Modifying the rc-scripts for
SHUTDOWN''

� Copy the following from you development filesystem to the rescue
system AND the new raid system

cd /root/raidboot
mkdir mnt
gzip -d rescue.clean
losetup /dev/loop0 rescue.clean
mount /dev/loop0 mnt

copy these files

cp -p /etc/* mnt/etc
cp -p /etc/rc.d/* mnt/etc/rc.d
{or as appropriate for your system}
cp -a /lib/modules/* mnt/lib/modules

Some Linux distributions include a test for the ro/rw status of the
root file system. The rc startup files need to have this test removed
for the initrd rescue system. See the instructions in the section on
``Correctons for Rescue System''.

Correct the entries in fstab to show /dev/md0 as the root device. Make
sure that the partition(s) you use for booting is included in fstab.

Create /etc/raidboot.conf which describes the raid boot configuration.
This file may NOT contain comments in the first three lines, after
that it doesn't matter.

raidboot.conf

/dev/sda1 /dev/sda2
raidboot
raid5.conf
# comments may only be placed 'after' the three
# configuration lines.
#
# This is '/etc/raidboot.conf'
#
# line one, the partition(s) containing the 'initrd' raid-rescue system
# It is not necessary to boot from these partitions, however,
# since the rescue system will not fit on floppy, it is necessary
# to know which partitions are to be used to load the rescue system
#
# line two, the path to the raidboot config information
# Where the shutdown status, etc... is located at boot time
# It does NOT include the mount point information, only 'path'
# /mntpoint/'path'
#
# line -3-, name of the raid configuration file
# Current raid configuration file i.e. raid1.conf, raid5.conf

A few more things to do and the raid systems is ready to boot.

Create ``rc.raidown'', as described in Appendix F, and copy it to
/etc/rc.d on the rescue, development, and raid system. Unmount the
rescue system and zip it.

umount mnt
losetup -d /dev/loop0
mv rescue.clean rescue
gzip rescue

Copy the rescue file to the raidboot partitions.

cp rescue.gz /mnt_point(1)/raidboot
cp rescue.gz /mnt_point(2)/raidboot

Activate the raid array.

mdadd -ar

Save the good reference status to the raidboot partition

cat /proc/mdstat | grep md0 > /mnt_point(1)/raidboot/raidgood.ref
cat /proc/mdstat | grep md0 > /mnt_point(1)/raidboot/raidgood.ref

Lastly, configure the boot program as outlined in ``Boot Time Configu�
ration Parameters'' and reboot your system onto the raid array.

4. initrd Cookbook for root mounted RAID

This is the procedure to make an 'initrd' ramdisk with rescue tools
for raid.

Specifically, this document referrs to RAID1 and RAID5
implementations.

4.1. Security Reminder

The rescue file system may be used stand alone. Should your raid array
fail to mount, you are left with the rescue system mounted and
running. TAKE THE APPROPRIATE SECURITY PRECAUTIONS!!!

4.2. Build the Kernel and Raid Tools

The first thing that must be done is to patch and build your kernel
and become familiar with the raid tools. Make sure and include
``Gadi's raid stop patch'' in Appendix E. Configure, mount and test
your raid device(s). The details of how to do this are included in the
raidtools package and briefly reviewed later in this document.

4.3. Build the initrd Rescue and Boot filesystem

I used the Slackware-3.4 distribution to build both the Rescue/Boot
filesystem and the filesystem for the production machine. Any linux
distribution should work fine. If you use a different distribution,
review the Slackware specific portion of this procedure and modify it
to suit your needs.

I use loadlin to boot the kernel image and ramdisk from a dos
partition simply because there are oddball devices in my system that
have dos configuration software. Lilo will work just as well and a
small linux partition can be used instead containing only the
raid/boot files and the lilo record.

For the raid boot/rescue system, I chose to create a minimum ramdisk
system using the Slackware 'setup' script followed by installing the
'linuxthreads' package and 'raidtools' over the clean Slackware
installation on my ramdisk. I used the identical procedure to build
the production system. So the rescue and production systems are very
similar.

This installation process gives me a 'bare' system (save a copy of the
file) to which I overlay

/lib/modules/2.x.x......
/etc .... with a modified fstab, mdtab, raidX.conf, raidboot.conf
/etc/rc.d
/dev/md*

from my current system to customize it for the particular kernel and
machine that it is/will-be running on.

This makes the boot/rescue system the same system that is running on
the root mounted raid device, just skinnyed down a bit, while allowing
the library, etc... revisions to always be current.

4.4. Start the STEP by STEP instructions

From the root home directory (/root):

cd /root
mkdir raidboot
cd raidboot

Create a mountpoints to work on

mkdir mnt
mkdir mnt2

Make a file large enough to do the file system install. This will be a
lot larger than the final rescue file system. I chose 24 megs since
16 megs is not large enough

dd if=/dev/zero of=build bs=1024k count=24

associate the file with a loop device and generate an ext2 file system
on the file

losetup /dev/loop0 build
mke2fs -v -m0 -L initrd /dev/loop0
mount /dev/loop0 mnt

4.5. Install the distribution - Slackware Specific

``...skip Slackware Specific stuff'' and go to next section.

Now that an empty filesystem is created and mounted, run "setup".

Specify /root/raidboot/mnt

as the 'target'. The source is whatever you normally install from.
Select the packages you wish to install and proceed but DO NOT
configure.

Choose 'EXPERT' prompting mode.

I chose 'A', 'AP, and 'N' installing only the minimum to run the
system plus an editor I am familiar with (vi, jed, joe) that is
reasonably compact.

lqqqqqqqq SELECTING PACKAGES FROM SERIES A (BASE LINUX SYSTEM) qqqqqqqqk
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk x
x x [X] aaa_base Basic filesystem, shell, and utils - REQUIRED x x
x x [X] bash GNU bash-1.14.7 shell - REQUIRED x x
x x [X] devs Device files found in /dev - REQUIRED x x
x x [X] etc System config files & utilities - REQUIRED x x
x x [X] shadow Shadow password suite - REQUIRED x x
x x [ ] ide Linux 2.0.30 no SCSI (YOU NEED 1 KERNEL) x x
x x [ ] scsi Linux 2.0.30 with SCSI (YOU NEED 1 KERNEL) x x
x x [ ] modules Modular Linux device drivers x x
x x [ ] scsimods Loadable SCSI device drivers x x
x x [X] hdsetup Slackware setup scripts - REQUIRED x x
x x [ ] lilo Boots Linux (not UMSDOS), DOS, OS/2, etc. x x
x x [ ] bsdlpr BSD lpr - printer spooling system x x
x x [ ] loadlin Boots Linux (UMSDOS too!) from MS-DOS x x
x x [ ] pnp Plug'n'Play configuration tool x x
x x [ ] umsprogs Utilities needed to use the UMSDOS filesystem x x
x x [X] sysvinit System V-like INIT programs - REQUIRED x x
x x [X] bin GNU fileutils 3.12, elvis, etc. - REQUIRED x x
x x [X] ldso Dynamic linker/loader - REQUIRED x x
x x [ ] ibcs2 Runs SCO/SysVr4 binaries x x
x x [X] less A text pager utility - REQUIRED x x
x x [ ] pcmcia PCMCIA card services support x x
x x [ ] getty Getty_ps 2.0.7e - OPTIONAL x x
x x [X] gzip The GNU zip compression - REQUIRED x x
x x [X] ps Displays process info - REQUIRED x x
x x [X] aoutlibs a.out shared libs - RECOMMENDED x x
x x [X] elflibs The ELF shared C libraries - REQUIRED x x
x x [X] util Util-linux utilities - REQUIRED x x
x x [ ] minicom Serial transfer and modem comm package x x
x x [ ] cpio The GNU cpio backup/archiving utility x x
x x [X] e2fsbn Utilities for the ext2 file system x x
x x [X] find GNU findutils 4.1 x x
x x [X] grep GNU grep 2.0 x x
x x [ ] kbd Change keyboard mappings x x
x x [X] gpm Cut and paste text with your mouse x x
x x [X] sh_utils GNU sh-utils 1.16 - REQUIRED x x
x x [X] sysklogd Logs system and kernel messages x x
x x [X] tar GNU tar 1.12 - REQUIRED x x
x x [ ] tcsh Extended C shell version 6.07 x x
x x [X] txtutils GNU textutils-1.22 - REQUIRED x x
x x [ ] zoneinfo Configures your time zone x x
x mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x

From the 'AP series, I use only 'JOE', and editor I like, and 'MC' a
small and useful file management tool. You choose the utilities you
will need on your system.

lqqqqqqqqq SELECTING PACKAGES FROM SERIES AP (APPLICATIONS) qqqqqqqqqk
x x [ ] ispell The International version of ispell x x
x x [ ] jove Jonathan's Own Version of Emacs text editor x x
x x [ ] manpgs More man pages (online documentation) x x
x x [ ] diff GNU diffutils x x
x x [ ] sudo Allow special users limited root access x x
x x [ ] ghostscr GNU Ghostscript version 3.33 x x
x x [ ] gsfonts1 Ghostscript fonts (part one) x x
x x [ ] gsfonts2 Ghostscript fonts (part two) x x
x x [ ] gsfonts3 Ghostscript fonts (part three) x x
x x [ ] jed JED programmer's editor x x
x x [X] joe joe text editor, version 2.8 x x
x x [ ] jpeg JPEG image compression utilities x x
x x [ ] bc GNU bc - arbitrary precision math language x x
x x [ ] workbone a text-based audio CD player x x
x x [X] mc The Midnight Commander file manager x x
x x [ ] mt_st mt ported from BSD - controls tape drive x x
x x [ ] groff GNU troff document formatting system x x
x x [ ] quota User disk quota utilities x x
x x [ ] sc The 'sc' spreadsheet x x
x x [ ] texinfo GNU texinfo documentation system x x
x x [ ] vim Improved vi clone x x
x x [ ] ash A small /bin/sh type shell - 62K x x
x x [ ] zsh Zsh - a custom *nix shell x x
x mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x

From the 'N' package I only loaded TCPIP. This isn't really neces�
sary, but is very handy and allows access to the network while working
on a repair or update with the root raid array dismounted. TCPIP also
contains 'biff' which is used by some of the applications in 'A'. If
you don't install 'N' you might want to install the biff package any�
way.

lqqqq SELECTING PACKAGES FROM SERIES N (NETWORK/NEWS/MAIL/UUCP) qqqqqk
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk x
x x [ ] apache Apache WWW (HTTP) server x x
x x [ ] procmail Mail delivery/filtering utility x x
x x [ ] dip Handles SLIP/CSLIP connections x x
x x [ ] ppp Point-to-point protocol x x
x x [ ] mailx The mailx mailer x x
x x [X] tcpip TCP/IP networking programs x x
x x [ ] bind Berkeley Internet Name Domain server x x
x x [ ] rdist Remote file distribution utility x x
x x [ ] lynx Text-based World Wide Web browser x x
x x [ ] uucp Taylor UUCP 1.06.1 with HDB && Taylor configs x x
x x [ ] elm Menu-driven user mail program x x
x x [ ] pine Pine menu-driven mail program x x
x x [ ] sendmail The sendmail mail transport agent x x
x x [ ] metamail Metamail multimedia mail extensions x x
x x [ ] smailcfg Extra configuration files for sendmail x x
x x [ ] cnews Spools and transmits Usenet news x x
x x [ ] inn InterNetNews news transport system x x
x x [ ] tin The 'tin' news reader (local or NNTP) x x
x x [ ] trn 'trn' for /var/spool/news x x
x x [ ] trn-nntp 'trn' for NNTP (install 1 'trn' maximum) x x
x x [ ] nn-spool 'nn' for /var/spool/news x x
x x [ ] nn-nntp 'nn' for NNTP (install 1 'nn' maximum) x x
x x [ ] netpipes Network pipe utilities x x
x mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x

With the installation complete, say no to everything else (no to all
configuration requests) and exit the script.

4.6. Install linux pthreads

Now you must install the 'linuxthreads-0.71' library. I have included
this diff for the linuxthreads Makefile rather than explain the
details of the installation by hand. Save the original Makefile,
apply the diff and then:

cd /usr/src/linuxthreads-0.71
patch
make
make install

-------------------diff Makefile.old Makefile.raid-----------------
2a3,13
> # If you are building "linuxthreads" for installation on a mount
> # point which is not the "root" partition, redefine 'BUILDIR' to
> # the mount point to use as the "root" directory
> # You may wish to do this if you are building an 'initial ram disk'
> # such as used with bootable root raid devices.
> # REQUIRES ldconfig version 1.9.5 or better
> # do ldconfig -v to check
> #
> BUILDIR=/root/raidboot/mnt
> #BUILDIR=
>
81,82c92,93
< install pthread.h $(INCLUDEDIR)/pthread.h
< install semaphore.h $(INCLUDEDIR)/semaphore.h
---
> install pthread.h $(BUILDIR)$(INCLUDEDIR)/pthread.h
> install semaphore.h $(BUILDIR)$(INCLUDEDIR)/semaphore.h
84c95
< test -f /usr/include/sched.h || install sched.h $(INCLUDEDIR)/sched.h
---
> test -f $(BUILDIR)/usr/include/sched.h || install sched.h $(BUILDIR)$(INCLUDEDIR)/sched.h
86,89c97,103
< install $(LIB) $(LIBDIR)/$(LIB)
< install $(SHLIB) $(SHAREDLIBDIR)/$(SHLIB)
< rm -f $(LIBDIR)/$(SHLIB0)
< ln -s $(SHAREDLIBDIR)/$(SHLIB) $(LIBDIR)/$(SHLIB0)
---
> install $(LIB) $(BUILDIR)$(LIBDIR)/$(LIB)
> install $(SHLIB) $(BUILDIR)$(SHAREDLIBDIR)/$(SHLIB)
> rm -f $(BUILDIR)$(LIBDIR)/$(SHLIB0)
> ln -s $(SHAREDLIBDIR)/$(SHLIB) $(BUILDIR)$(LIBDIR)/$(SHLIB0)
> ifneq ($(BUILDIR),)
> ldconfig -r ${BUILDIR} -n $(SHAREDLIBDIR)
> else
91c105,106
< cd man; $(MAKE) MANDIR=$(MANDIR) install
---
> endif
> cd man; $(MAKE) MANDIR=$(BUILDIR)$(MANDIR) install

4.7. Install Raid Tools

The next step is the installation of the raid tools. raidtools-0.42

You must run the "configure" script to point the Makefile at the build
directory for the ramdisk files
cd /usr/src/raidtools-0.42
configure --sbindir=/root/raidboot/mnt/sbin --prefix=/root/raidboot/mnt/usr
make
make install

Now!! the Makefile for install is not quite right so do the following
to clean up. This will be fixed in future releases so that the re-
linking will not be necessary.

Fix the make install error

The file links specified in the Makefile at 'LINKS' must be removed
and re-linked to operate properly.

cd /root/raidboot/mnt/sbin
ln -fs mdadd mdrun
ln -fs mdadd mdstop

4.8. Remove un-needed directories and files from new filesystem.

Delete the following directories from filesystem (CAUTION DON'T DELETE
FROM YOUR RUNNING SYSTEM) it's easy to do, guess how I found out!!!

cd /root/raidboot/mnt
rm -r home/ftp/*
rm -r lost+found
rm -r usr/doc
rm -r usr/info
rm -r usr/local/man
rm -r usr/man
rm -r usr/openwin
rm -r usr/share/locale
rm -r usr/X*
rm -r var/man
rm -r var/log/packages
rm -r var/log/setup
rm -r var/log/disk_contents

4.9. Create /dev/md x

The last step simply copies the /dev/md* devices from the current file
system onto the rescue file system. You could create these with
mknode.

cp -a /dev/md* /root/raidboot/mnt/dev

4.10. Create a bare filesystem suitable for initrd

Now you have a clean re-useable filesystem ready for customization.
Once customized, this file system can be used for rescue should the
raid device(s) become corrupted and the raid tools needed to fix them.
It will also be used to boot and root-mount the raid device by adding
the linuxrc file which will be discussed next.

Copy the file system to a smaller device for the initrd file, 16 megs
should be large enough.

Create the smaller file system and mount it

cd /root/raidboot
dd if=/dev/zero of=bare.fs bs=1024k count=16

associate the file with a loop device and generate a ext2 file system
on the file

losetup /dev/loop1 bare.fs
mke2fs -v -m0 -L initrd /dev/loop1
mount /dev/loop1 mnt2

Copy the 'build' file system to 'bare.fs'

cp -a mnt/* mnt2

Save the 'bare.fs' system before customization so later update is
easy. The 'build' file system is no longer needed and may be deleted.

cd /root/raidboot
umount mnt
umount mnt2
losetup -d /dev/loop0
losetup -d /dev/loop1
rm build
cp bare.fs rescue
gzip -9 bare.fs

4.10.1. Create the BOOT/RESCUE initrd filesystem

Now copy the system dependent items that match the kernel from the
development platform, or you can manually modify the files in the
rescue file system to match your target system.

losetup /dev/loop0 rescue
mount /dev/loop0 mnt

Make sure your etc directory is clean of *~, core and log files. The
next 2 commands creates some warning messages, ignore them.

cp -dp /etc/* mnt/etc
cp -dp /etc/rc.d/* mnt/etc/rc.d

mkdir mnt/lib/modules
cp -a /lib/modules/2.x.x mnt/lib/modules <--- your current 2.x.x

4.10.2. Corrections for the Rescue System

Edit the following files to correct them for your rescue system. Some
file names listed below are Slackware specific but have equivalents in
other distributions.

cd mnt

Non-network
etc/fstab
etc/mdtab should work OK
Network
etc/hosts
etc/resolv.conf
etc/hosts.equiv and related files
etc/rc.d/rc.inet1 correct ip#, mask, gateway, etc...
etc/rc.d/rc.S remove entire section on file system status
from:
# Test to see if the root partition is read-only
to but not including:
# remove /etc/mtab* so that mount will .....
This avoids the annoying warning that
the ramdisk is mounted rw.
etc/rc.d/rc.xxxxx others as required, see later on in this doc
root/.rhosts if present
home/xxxx/xxxx others as required

WARNING: The above procedure moves your password and shadow
files onto the rescue disk!!!!!

WARNING: You may not wish to do this for security reasons.

Create any directories for mounting /dev/disk... as may be required
that are unique to your system. These are the mountpoints for booting
the system (boot partition and backup boot partition). My system boot
from dos using loadlin, however linux partition(s) and lilo will work
fine. My system uses:

cd /root/raidboot/mnt <--- initrd root
mkdir dosa dos partition mount point
mkdir dosb dos mirror mount point

The rescue file system is complete!

You will note upon examination of the files in the rescue file system,
that there are still many files that could be deleted. I have not
done this since it would overly complicate this procedure and most
raid systems have adequate disk and memory. If you wish to skinny
down the file system, go to it!

4.11. Making 'initrd' boot the RAID device - linuxrc

To make the rescue disk boot the raid device, you need only copy the
executable script file:

linuxrc

to the root of the device.

The theory of operation for this linuxrc file is discussed in
``Appendix G, linuxrc theory of operation''.

A very simple and much easier to understand (working) linuxrc is
included in ``Appendix D'', obsolete linuxrc and shutdown scripts.
Copy the following text to linuxrc and save in your development area.

-------------------- linuxrc ----------------------
#!/bin/sh
# ver 1.13 3-6-98
#
################# BEGIN 'linuxrc' ##################
# DEFINE FUNCTIONS #
####################################################
# Define 'Fault' function in the event something
# goes wrong during the execution of 'linuxrc'
#
FaultExit () {
# correct fstab to show '/dev/ram0' for rescue system
/bin/cat /etc/fstab | {
while read Line
do
if [ -z "$( echo ${Line} | /usr/bin/grep md0 )" ]; then
echo ${Line}
else
echo "/dev/ram0 / ext2 defaults 1 1"
fi
done
} > /etc/tmp.$$
/bin/mv /etc/tmp.$$ /etc/fstab
# point root at /dev/ram0 (the rescue system)
echo 0x100>/proc/sys/kernel/real-root-dev
/bin/umount /proc
exit
}

# Define 'Warning' procdure to print banner on boot terminal
#
Warning () {
echo '*********************************'
echo -e " $*"
echo '*********************************'
}

# Define 'SplitKernelArg' to help extract 'Raid' related kernel arguments
SplitKernelArg () { eval $1='$( IFS=,; echo $2)' }

#Define 'SplitConfArgs' to help extract system configuration arguments
SplitConfArgs () {
RaidBootType=$1
RaidBootDevice=$2
RaidConfigPath=$3
}
########################################################
################### MAIN linuxrc #######################
########################################################
# mount the proc file system
/bin/mount /proc

# Get the boot partition and configuration location from command line
CMDLINE=`/bin/cat /proc/cmdline`
for Parameter in $CMDLINE; do
Parameter=$( IFS='='; echo ${Parameter} )
case $Parameter in
Raid*) SplitKernelArg $Parameter;;
esac
done

# check for 'required raid boot'
if [ -z "${Raid_Conf}" ]; then
Warning Kernel command line \'Raid_Conf\' missing
FaultExit
fi
SplitConfArgs $Raid_Conf

# tmp mount the boot partition
/bin/mount -t ${RaidBootType} ${RaidBootDevice} /mnt

# get etc files from primary raid system
pushd /etc

# this will un-tar into 'etc' (see rc.6)
if [ ! -f /mnt/${RaidConfigPath}/raidboot.etc ]; then
# bad news, this file should be here
Warning required file \'raidboot.etc\' \
missing from ${RaidBootDevice}/${RaidConfigPath} \\n \
\\tUsing rescue system defaults
else
/bin/tar -xf /mnt/${RaidConfigPath}/raidboot.etc
fi
# get 'real' raidboot device for this boot
# status path, and name of raidX.conf
if [ ! -f /mnt/${RaidConfigPath}/raidboot.cfg ]; then
# bad news, this file should be here
Warning required file 'raidboot.cfg' \
missing from ${RaidBootDevice}/${RaidConfigPath}\\n \
\\tUsing rescue system defaults
# Get the first raidX.conf file name in $RArg1
RaidBootDevs=$RaidBootDevice
RaidStatusPath=$RaidConfigPath
for RaidConfigEtc in $( ls raid*.conf )
do break; done
else
{
read RaidBootDevs
read RaidStatusPath
read RaidConfigEtc
} < /mnt/${RaidConfigPath}/raidboot.cfg

fi
popd
/bin/umount /mnt

# Set a flag in case the raid status file is not found
#
RAIDOWN="raidboot.ro not found"
RAIDREF="raidgood.ref not found"
echo "Reading md0 shutdown status."

# search for raid shutdown status
for Device in ${RaidBootDevs}
do
# these filesystem types should be in 'fstab' since
# the partitions must be mounted for a clean raid shutdown
/bin/mount ${Device} /mnt
if [ -f /mnt/${RaidStatusPath}/raidboot.ro ]; then
RAIDOWN=`/bin/cat /mnt/${RaidStatusPath}/raidboot.ro`
RAIDREF=`/bin/cat /mnt/${RaidStatusPath}/raidgood.ref`
/bin/umount /mnt
break
fi
/bin/umount /mnt
done
# Test for a clean shutdown with array matching reference
if [ "${RAIDOWN}" != "${RAIDREF}" ]; then
Warning shutdown ERROR ${RAIDOWN}
FaultExit
fi

# The raid array is clean, remove shutdown status files
for Device in ${RaidBootDevs}
do
/bin/mount ${Device} /mnt
/bin/rm -f /mnt/${RaidStatusPath}/raidboot.ro
/bin/umount /mnt
done

# Write a clean superblock on all raid devices

echo "write clean superblocks"
/sbin/mkraid -f --only-superblock /etc/${RaidConfigEtc}

# Activate raid array(s)
if [ -z "$Raid_ALT" ]; then
/sbin/mdadd -ar
else
/sbin/mdadd $Raid_ALT
fi

# If there are errors - BAIL OUT and leave rescue running
if [ $? -ne 0 ]; then
Warning some RAID device has errors
FaultExit
fi

# Everything is fine, let the kernel mount /dev/md0
# tell the kernel to switch to /dev/md0 as the /root device
# The 0x900 value is the device number calculated by:
# 256*major_device_number + minor_device number
echo "/dev/md0 mounted on root"
echo 0x900>/proc/sys/kernel/real-root-dev
# umount /proc to deallocate initrd device ram space
/bin/umount /proc
exit
#------------------ end linuxrc ----------------------

Add 'linuxrc' to initrd boot device

cd /root/raidboot
chmod 777 linuxrc
cp -p linuxrc mnt

4.12. Modifying the rc-scripts for SHUTDOWN

To complete the installation, modify the rc scripts to save the md
status to the real root device when shutdown occurs.

In slackware this is rc.0 -> rc.6
In debian 'bo' this is in both 'halt' and 'reboot'

If you implement this in another distribution, please e-mail
the instructions and sample files so they can be included here.

I have modified Bohumil Chalupa's raid stop work-around slightly. His
original solution is presented in ``Appendix A''.

Since there are no linux partitions left on the production system
except md0, the boot partitions are used to store the raidOK readonly
status. I chose to write a file to each of the duplicate boot
partitions containing the status of the md array at shutdown and
signifying that the md device has been remounted RO. This allows the
system to be fail safe when any of the hard drives die.

The shutdown script is modified to call ``rc.raidown'' which saves the
necessary information to successfully reboot and mount the raid
device. Examples of shutdown scripts for various linux distributions
are shown in ``Appendix B''.

To capture the raid array shutdown status insert a call to
``rc.raidown'' after any case statements (if present) but before the
actual shutdown (kills, status saves, etc...) begins and before the
file systems are dismounted.

############ Save raid boot and status info ##############
#
if [ -x /etc/rc.d/rc.raidown ]; then
/etc/rc.d/rc.raidown
fi
################## end raid boot #########################

After all the file systems are dismounted (the root file system

################ for raid arrays #########################
# Stop all known raid arrays (except root which won't stop)
if [ -x /sbin/mdstop ]; then
echo "Stopping raid"
/sbin/mdstop -a
fi
##########################################################

This will cleanly stop all raid devices except root. Root status is
passed to the next boot in raidstat.ro.

Copy the rc file to your new raid array, the rescue file system that
is still mounted on /root/raidboot/mnt and the development system if
it is on the same machine.

Modify rescue etc/fstab as needed and make sure rescue mdtab is
correct.

Now copy the rescue disk to your dos partition and everything should
be ready to boot the raid device as root.

umount mnt
losetup -d /dev/loop0
gzip -9 rescue

Copy rescue.gz to your boot partitions.

All that remains is to creat the configuration file raidboot.conf and
test the new file system by rebooting.

4.13. Configuring RAIDBOOT - raidboot.conf

The comments following the example configuration file explain each of
the three lines. This example file is for a 4 drive raid5 scsii array
with duplicate boot partitions on drives sda1 and sdb1. Put the
paramaters descriptive of your file systems here instead.

/dev/sda1 /dev/sdb1
linux
raid5.conf
# comments may only be placed 'after' the three
# configuration lines.
#
# This is 'raidboot.conf'
#
# line one, the partition(s) containing the 'initrd' raid-rescue system
# It is not necessary to boot from these partitions, however,
# since the rescue system will not fit on floppy, it is necessary
# to know which partitions are to be used to load the rescue system
#
# line two, the path to the raidboot config information
# Where the shutdown status, etc... is located at boot time
# It does NOT include the mount point information, only 'path'
# /mntpoint/'path'
#
# line -3-, name of the raid configuration file
# Current raid configuration file i.e. raid1.conf, raid5.conf

4.14. Kernel 'loadlin and lilo' variables for RESCUE and RAID

There are two kernel variables for the RESCUE and RAID system, only
the first need be specified.

� Raid_Conf=msdos,/dev/sda1,raidboot

This variable points to raid boot device and configuration
file. For floppy rescue boot, you may want to specify this
on the kernel command line or in the loadlin or lilo boot
file

format: 'filesystem-type,device,path-to-config-from-mount�
point'

� Raid_ALT=-r,-p5,/dev/md0,/dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3

Alternate mdadd parameters necessary when booting with non-
redundant raid array. These are the comma separated command
line parameters for mdadd. Unless they are needed to start a
failed/non-redundant array, COMMENT OUT OR SPECIFY WITH A
'NULL'.

i.e. Raid_ALT=

Either of these parameters may be specified in the lilo or loadlin
boot parameter file or on the loadlin kernel command line. Care must
be taken that the maximum line length is not exceeded, however, if the
command line is used (128 characters).

When booting with lilo, the parameters are included in the lilo config
file in the form:

append="Raid_Conf=msdos,/dev/sda1,raidboot"
append="Raid_ALT=-r,-p5,/dev/md0,/dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3"

See man lilo.conf for more detailed information.

Since I have some hardware that requires DOS configuration utilities,
I have a small dos partition on the system. Therefore, I used loadlin
to boot the raid5 system from the dos partition with a mirror (copy)
on the companion disk. An identical method is used for the raid1
system. The example below uses loadlin, but the procedure is very
similar for lilo.

My dos root system contains a small editor among the utilities so I
can modify the boot parameters of loadlin if necessary, allowing me to
reboot the linux system on my swap disk while testing.

The dos system contains this tree for linux"

c:\raidboot.bat
c:\raidboot\loadlin.exe
c:\raidboot\zimage
c:\raidboot\rescue.gz
c:\raidboot\raidboot.cfg
c:\raidboot\raidboot.etc
c:\raidboot\raidgood.ref
c:\raidboot\raidstat.ro (only at shutdown)

---------------------- linux.bat ---------------------------
echo "Start the LOADLIN process:"
c:\raidboot\loadlin @c:\raidboot\boot.par
-------------------- end linux.bat -------------------------

boot.par contains:

# loadlin boot parameter file
#
# version 1.02 3-6-98

# linux kernel image
c:\linux\zimage

# target root device
root=/dev/md0
#root=/dev/ram0
#root=/dev/sdc5

# mount root device as 'ro'
ro

# size of ram disk
ramdisk_size=16384

# initrd file name
initrd=c:\raidboot\rescue.gz
#noinitrd

# memory ends here
mem=131072k

# points to raid boot device, configuration file
# for floppy rescue boot, you may want to specify
# this on the command line instead of here
# format 'filesystem-type,device,path-to-config-frm_mntpnt'
Raid_Conf=msdos,/dev/sda1,raidboot

# Alternate mdadd parameters
# necessary when boot with non-redundant raid
# otherwise, COMMENT OUT OR SPECIFY 'NULL'
#Raid_ALT=-r,-p5,/dev/md0,/dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3

# ethernet devices
ether=10,0x300,eth0

***** >> NOTE!! the only difference between forcing the rescue system to
run and the raid device mounting, is the loadlin parameter

root=/dev/ram0 for the rescue system
root=/dev/md0 for RAID

With root=/dev/ram0 the RAID device will not mount
and the rescue system will run unconditionally.

If the RAID array fails, the rescue system is left mounted and
running.

5. Configuring the Production RAID system.

5.1. Two systems with identical motherboards were configured. System
specs.

Raid-1 Raid-5
Motherboard: Iwill P55TU dual ide adaptec scsi
Processor: Intel P200
Disks: 2ea 7 gig 4 ea Segate 4.2 gig
Maxtors wide scsii

The disk drives are designated by linux as 'sda' through 'sdd' on the
raid5 system and 'hda' and 'hdc' on the raid1 system.

5.2. Partitioning the hard drives.

Since testing a large root mountable RAID array is difficult because
of the ckraid re-boot problem, I re-partitioned my swap space to
include a smaller RAID partition for testing purposes,
sda6,sdb6,sdc6,sdd6, and a small root and /usr/src partition pair for
developing and testing the raid kernel and tools. You may find this
helpful.

<bf/DEVELOPMENT SYSTEM - RAID5/
Device System Size Purpose

/dev/sda1 dos boot 16 meg boot partition
* /dev/sda2 extended 130 meg (see below)
/dev/sda3 linux native 4 gig primary raid5-1
----------------------sda2------------------------------
* /dev/sda5 linux swap 113 meg SWAP space
* /dev/sda6 linux native 16 meg test raid5-1
========================================================
/dev/sdb1 dos boot 16 meg boot partition duplicate
* /dev/sdb2 extended 130 meg (see below)
/dev/sdb3 linux native 4 gig primary raid5-2
----------------------sdb2------------------------------
* /dev/sdb5 linux swap 113 meg SWAP space
* /dev/sdb6 linux native 16 meg test raid5-2
========================================================
* /dev/sdc2 extended 146 meg (see below)
/dev/sdc3 linux native 4 gig primary raid5-3
----------------------sdc2------------------------------
* /dev/sdc5 linux swap 130 meg development root partition
* /dev/sdc6 linux native 16 meg test raid5-3
========================================================
* /dev/sdd2 extended 146 meg (see below)
/dev/sdd3 linux native 4 gig primary raid5-4
----------------------sdd2------------------------------
* /dev/sdd5 linux swap 130 meg development /usr/src
* /dev/sdd6 linux native 16 meg test raid5-4

<bf/DEVELOPMENT SYSTEM - RAID1/
Device System Size Purpose

/dev/hda1 dos 16meg boot partition
* /dev/hda2 extended 126m (see below)
/dev/hda3 linux 126m development root partition
/dev/hda4 linux 6+gig raid1-1
----------------------hda2------------------------------
* /dev/hda5 linux 26m test raid1-1
* /dev/hda6 linux swap 100m
========================================================

/dev/hdc1 is simply an exact copy of hda1 so the
partion can be made active if hda fails
* /dev/hdc2 extended 126m (see below)
/dev/hdc3 linux 126m development /usr/src
/dev/hdc4 linux 6+gig raid1-2
----------------------hdc2------------------------------
* /dev/hdc5 linux 26m test raid1-2
* /dev/hdc6 linux swap 100m

The sdx2 and hdx3 partitions were switched to 'swap' after developing
this utility. I could have done it on another machine, however, the
libraries and kernels are all about a year or more out of date on my
other linux boxes and I preferred to build it on the target machine.

The partitioning scheme was chosen so that in the event that any one
of the drives fails catastrophically, the system will continue to run
and be bootable with minimum effort and NO data loss.

� If any single hard drive fails, the boot will abort, and the rescue
system will run. Examination of the screen message or
/dosx/raidboot/raidstat.ro will tell the operator the status of the
failed array.

� If sda1 (raid5) or hda1 (raid1) fails, the dos backup boot
partition must be made 'active' and the bios must recognize the new
partition as the boot device or it must be physically be moved to
the xda position. Alternatively, the system could be booted from a
floppy disk using the initrd image on the remaining backup boot
drive. The raid system can then be made active again by issuing:

"/sbin/mkraid /etc/raid<it/x/.conf -f --only-superblock"

to rebuild the remaining superblock(s).

� Once this is done, then

mdadd -ar

� Examine the status of the array to verify that everything is OK
then replace the good array reference with the current status until
the failed disk can be repaired or replaced.

cat /proc/mdstat | grep md0 > /dosx/raidboot/raidgood.ref

shutdown -r now

to do a clean reboot, and the system is up again.

6. Building the RAID file system.

This description is for my RAID systems described in the system specs.
Your system may have a different RAID architecture, so modify as
appropriate. Please read the man pages and QuickStart.RAID that come
with the raidtools-0.42

6.1. /etc/raid5.conf

# raid-5 configuration
raiddev /dev/md0
raid-level 5
nr-raid-disks 4
chunk-size 32

# Parity placement algorithm
parity-algorithm left-symmetric

# Spare disks for hot reconstruction
#nr-spare-disks 0

device /dev/sda3
raid-disk 0

device /dev/sdb3
raid-disk 1

device /dev/sdc3
raid-disk 2

device /dev/sdd3
raid-disk 3

6.2. /etc/raid1.conf

# raid-1 configuration
raiddev /dev/md0
raid-level 1
nr-raid-disks 2
nr-spare-disks 0

device /dev/hda4
raid-disk 0

device /dev/hdc4
raid-disk 1

6.3. Step by Step procedures for building production RAID file sys�
tem.

For my RAID5 system I did a complete install of:

Slackware-3.4 any current distribution should work OK
linuxthreads-0.71
raidtools-0.42
linux-2.0.33 with raid145 patch and Gadi's patch

Create and format the raid device.

mkraid /etc/raid5.conf
mdcreate raid5 /dev/md0 /dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3
mdadd -ar
mke2fs /dev/md0
mkdir /md
mount -t ext2 /dev/md0 /md

Create the reference files that reboot will use, this may be different
on your system.

cat /proc/mdstat | grep md0 > /dosa/raidboot/raidgood.ref
cat /proc/mdstat | grep md0 > /dosb/raidboot/raidgood.ref

Use Slackware-3.4 or another distribution to build your OS

setup

Specify '/md' as the target, and the source whatever your normally
use. Select and install the disksets of interest except for the ker�
nel. Configure the system, but skip the section on lilo and kernel
booting. Exit setup.

Install 'pthreads'

cd /usr/src/linuxthreads-0.71

edit the Makefile and specify

BUILDIR=/md

make
make install

Install 'raidtools'

cd /usr/src/raidtools-0.42
configure --sbindir=/md/sbin --prefix=/md/usr

fix the raidtools make install error

cd /md/sbin
rm mdrun
rm mdstop
ln -s mdadd mdrun
ln -s mdadd mdstop

Create /dev/mdx

cp -a /dev/md* /md/dev

Add the system configuration from the current system (ignore errors).

cp -dp /etc/* mnt/etc
cp -dp /etc/rc.d/* mnt/etc/rc.d (include the new rc.6)
mkdir mnt/lib/modules
cp -a /lib/modules/2.x.x mnt/lib/modules <--- your current 2.x.x

Edit the following files to correct them for your file system

cd /md

Non-network
etc/fstab correct for real root and raid devices.
etc/mdtab should work OK
Network
etc/hosts
etc/resolv.conf
etc/hosts.equiv and related files
etc/rc.d/rc.inet1 correct ip#, mask, gateway, etc...
etc/rc.d/rc.S remove entire section on file system status
from:
# Test to see if the root partition isread-only
to but not including:
# remove /etc/mtab* so that mount will .....
This avoids the annoying warning that
the ramdisk is mounted rw.
etc/rc.d/rc.xxxxx others as required
root/.rhosts if present
home/xxxx/xxxx others as required

WARNING: The above procedure moves your password and shadow
files onto the new file system!!!!!

WARNING: You may not wish to do this for security reasons.

Create any directories for mounting /dev/disk... as may be required
that are unique to your system. Mine need:

cd /md <--- new file system root
mkdir dosa dos partition mount point
mkdir dosb dos mirror mount point

The new file system is complete. Make sure and save the md reference
status to the 'real' root device and you are ready to boot.

mount the dos partitions on dosa and dosb

cat /proc/mdstat | grep md0 > /dosa/raidboot/raidgood.ref
cat /proc/mdstat | grep md0 > /dosb/raidboot/raidgood.ref

mdstop /dev/md0

7. One last thought.

Remember that an expert is someone who knows at least 1% more than you
do about a subject. Bear this in mind when you e-mail me for help.
I'll try, but I've only done this once for raid1 and once for raid5!

Michael Robinton [email protected] <mailto:[email protected]>

8. Appendix A. - Bohumil Chalupa's md0 shutdown

Bohumil Chalupa's post to the linux raid list on the work around for
the raid1 + 5 mdstop problem. His solution does not address the
possibility of the raid device being corrupt at shutdown. So I have
added a simple status comparison to a good reference status at boot.
This allows the operator to intervene if something is wrong with a
disk in the array. The description of this is in the main body of this
document.

> From: Bohumil Chalupa <[email protected]>
>
> I can now boot initrd and use linuxrc to start the RAID1 array,
> then successfully switch root to /dev/md0.
>
> I don't know, however, any way how to cleanly _stop_ the array.

Well. I have to answer myself :-)

> Date: Mon, 29 Dec 1997 02:21:38 -0600 (CST)
> From: Edward Welbon <[email protected]>
> Subject: Re: dismounting root raid device
>
> For md devices other than raid0, there is probably state that needs to
> be saved that is only known once all writes have completed. Such state
> of course can't be saved to root once it is mounted readonly. In that
> case, you would have to be able to mount a writeable filesystem "X"
> on the readonly root and be able to write to "X" (I recall doing this
> during "rescue" operations, but not as an automated procedure).
>
> The filesystem "X" would presumably be a boot device from which the raid
> (during linuxrc exection via initrd) would pickup it's initial state from.
> Fortunately raid0 isn't required to write out any state (though it would
> be pleasant to be able to write the check sums to mdtab after an mdstop).
> Eventually, I will fiddle with this but it doesn't seem difficult though
> the "devil" is always in the "details".

Yes, that's it.
I had this idea in mind for some time already, but had no time to try it.
Yesterday I did, and it works.

With my RAID1 (mirror), I don't save any checksums or raid superblock data.
I only save an information on the "real" boot partition, that the root md
volume was remounted readonly during shutdown. Then, during boot, the
linuxrc script runs mkraid --only-superblock when it finds this
information; otherwise, it runs ckraid.
This means, that the raid superblock information is not updated during
shutdown; it's updated at the boot time.
It is not very clean, I'm afraid, :-( but it works.

I'm using Slackware and initrd.md by Edward Welbon to boot the root raid
device.
As far as I remember now, the only modified files are
mkdisk and linuxrc, and /etc/rc.d/rc.6 shutdown script.
And lilo.conf, of course.

I'm appending the important parts.

Bohumil Chalupa

--------------- my.linuxrc follows -----------------
#!/bin/sh
# we need /proc
/bin/mount /proc
# start up the md0 device. let the /etc/rc.d scripts get the rest of them
# we should do as little as possible here
# ________________________________________
# root raid1 shutdown test & recreation
# /start must be created on the rd image in my.mkdisk
echo "preparing md0: mounting /start"
/bin/mount /dev/sda2 /start -t ext2
echo "reading saved md0 state from /start"
if [ -f /start/root.raid.ok ]; then
echo "raid ok, modyfying superblock"
rm /start/root.raid.ok
/sbin/mkraid /etc/raid1.conf -f --only-superblock
else
echo "raid not clean, runing ckraid --fix"
/sbin/ckraid --fix /etc/raid1.conf
fi
echo "unmounting /start"
/bin/umount /start
# _________________________________________
#
echo "adding md0 for root file system"
/sbin/mdadd /dev/md0 /dev/sda1 /dev/sdb1
echo "starting md0"
/sbin/mdrun -p1 /dev/md0
# tell kernel we want to switch to /dev/md0 as root device, the 0x900 value
# is arrived at via 256*major_device_number + minor_device number.
echo "setting real-root-dev"
/bin/echo 0x900>/proc/sys/kernel/real-root-dev
# unmount /proc so that the ram disk can be deallocated.
echo "unmounting /proc"
/bin/umount /proc
/bin/echo "We are hopefully ready to mount /dev/md0 (major 9, minor 0) as
root"
exit
--------------- end of my.linuxrc ----------------------------------

----------- extract from /etc/rc.d/rc.6 follows -----------------
# Turn off swap, then unmount local file systems.
echo "Turning off swap."
swapoff -a
echo "Unmounting local file systems."
umount -a -tnonfs
# Don't remount UMSDOS root volumes:
if [ ! "`mount | head -1 | cut -d ' ' -f 5`" = "umsdos" ]; then
mount -n -o remount,ro /
fi

# Save raid state
echo "Saving RAID state"
/bin/mount -n /dev/sda2 /start -t ext2
touch /start/root.raid.ok
/bin/umount -n /start

-------------- end of excerpt from rc.6 ------------------------

------------------ part of my.mkdisk follows ----------------------
#
# now we have the filesystem ready to be populated, we need to
# get a few important directories. I had endless trouble till
# I created a pristine mtab. In my case, it is convenient that
# /etc/mdtab is copied over, this way I can activate md with
# a simple "/sbin/mdadd -ar" in linuxrc.
#
cp -a $ROOT/etc $MOUNTPNT 2>cp.stderr 1>cp.stdout
rm -rf $MOUNTPNT/etc/mtab
rm -rf $MOUNTPNT/etc/ppp*
rm -rf $MOUNTPNT/etc/termcap
rm -rf $MOUNTPNT/etc/sendmail*
rm -rf $MOUNTPNT/etc/rc.d
rm -rf $MOUNTPNT/etc/dos*
cp -a $ROOT/sbin $ROOT/dev $ROOT/lib $ROOT/bin $MOUNTPNT 2>>cp.stderr
1>>cp.stdout
# _____________________________________________________________________
# RAID: will need mkraid and ckraid
cp -a $ROOT/usr/sbin/mkraid $ROOT/usr/sbin/ckraid $MOUNTPNT/sbin
2>>cp.stderr 1>>cp.stdout
# ---------------------------------------------------------------------
# it seems that init wont come out to play unless it has utmp. this can
# probably be pruned back alot. no telling what the real bug was 8-).
#
mkdir $MOUNTPNT/var $MOUNTPNT/var/log $MOUNTPNT/var/run $MOUNTPNT/initrd
touch $MOUNTPNT/var/run/utmp $MOUNTPNT/etc/mtab
chmod a+r $MOUNTPNT/var/run/utmp $MOUNTPNT/etc/mtab
ln -s /var/run/utmp $MOUNTPNT/var/log/utmp
ln -s /var/log/utmp $MOUNTPNT/etc/utmp
ls -lstrd $MOUNTPNT/etc/utmp $MOUNTPNT/var/log/utmp $MOUNTPNT/var/run/utmp
#
# since I wanted to change the mount point, I needed this though
# I suppose that I could have done a "mkdir /proc" in linuxrc.
#
mkdir $MOUNTPNT/proc
chmod 555 $MOUNTPNT/proc
#
# ------------------------------------------------------
# we'll mount the real boot device to /start temporarily
# to check the root raid state saved at shutdown time
#
mkdir $MOUNTPNT/start
# -------------------------------------------------------
#
# need linuxrc (it is, after all, the point of this exercise).
#
if [ -x ./my.linuxrc ]; then
cp -a ./my.linuxrc $MOUNTPNT/linuxrc
chmod 777 $MOUNTPNT/linuxrc
else
ln -s /bin/sh $MOUNTPNT/linuxrc
fi
#
----------------- part of my.mkdisk ends -----------------

9. Appendix B. - Sample SHUTDOWN scripts

� ``Slackware''

� ``Debian''

9.1. Slackware - /etc/rc.d/rc.6

#! /bin/sh
#
# rc.6 This file is executed by init when it goes into runlevel
# 0 (halt) or runlevel 6 (reboot). It kills all processes,
# unmounts file systems and then either halts or reboots.
#
# Version: @(#)/etc/rc.d/rc.6 1.50 1994-01-15
#
# Author: Miquel van Smoorenburg <[email protected]>
# Modified by: Patrick J. Volkerding, <[email protected]>
#
# Modified by: Michael A. Robinton < [email protected] >
# to add call to rc.raidown
# Set the path.
PATH=/sbin:/etc:/bin:/usr/bin

# Set linefeed mode to avoid staircase effect.
stty onlcr

echo "Running shutdown script $0:"

# Find out how we were called.
case "$0" in
*0)
message="The system is halted."
command="halt"
;;
*6)
message="Rebooting."
command=reboot
;;
*)
echo "$0: call me as \"rc.0\" or \"rc.6\" please!"
exit 1
;;
esac

############ Save raid boot and status info ##############
#
if [ -x /etc/rc.d/rc.raidown ]; then
/etc/rc.d/rc.raidown
fi
################## end raid boot #########################

# Kill all processes.
# INIT is supposed to handle this entirely now, but this didn't always
# work correctly without this second pass at killing off the processes.
# Since INIT already notified the user that processes were being killed,
# we'll avoid echoing this info this time around.
if [ "$1" != "fast" ]; then # shutdown did not already kill all processes
killall5 -15
killall5 -9
fi

# Try to turn off quota and accounting.
if [ -x /usr/sbin/quotaoff ]
then
echo "Turning off quota."
/usr/sbin/quotaoff -a
fi
if [ -x /sbin/accton ]
then
echo "Turning off accounting."
/sbin/accton
fi

# Before unmounting file systems write a reboot or halt record to wtmp.
$command -w

# Save localtime
[ -e /usr/lib/zoneinfo/localtime ] && cp /usr/lib/zoneinfo/localtime /etc

# Asynchronously unmount any remote filesystems:
echo "Unmounting remote filesystems."
umount -a -tnfs &

# Turn off swap, then unmount local file systems.
echo "Turning off swap."
swapoff -a
echo "Unmounting local file systems."
umount -a -tnonfs
# Don't remount UMSDOS root volumes:
if [ ! "`mount | head -1 | cut -d ' ' -f 5`" = "umsdos" ]; then
mount -n -o remount,ro /
fi

################ for raid arrays #########################
# Stop all known raid arrays (except root which won't stop)
if [ -x /sbin/mdstop ]; then
echo "Stopping raid"
/sbin/mdstop -a
fi
##########################################################

# See if this is a powerfail situation.
if [ -f /etc/powerstatus ]; then
echo "Turning off UPS, bye."
/sbin/powerd -q
exit 1
fi

# Now halt or reboot.
echo "$message"
[ ! -f /etc/fastboot ] && echo "On the next boot fsck will be FORCED."
$command -f
############### end rc.6 #################################

9.2. Debian bo - /etc/init.d/halt and /etc/init.d/reboot

The modifications shown here for Debian bo halt and reboot files are
NOT TESTED. When you test this, please e-mail me so I can remove this
comment.

9.2.1. /etc/init.d/halt

#! /bin/sh
#
# halt The commands in this script are executed as the last
# step in runlevel 0, ie halt.
#
# Version: @(#)halt 1.10 26-Apr-1997 [email protected]
#

PATH=/sbin:/bin:/usr/sbin:/usr/bin

############ Save raid boot and status info ##############
#
if [ -x /etc/rc.d/rc.raidown ]; then
/etc/rc.d/rc.raidown
fi
################## end raid boot #########################

# Kill all processes.
echo -n "Sending all processes the TERM signal... "
killall5 -15
echo "done."
sleep 5
echo -n "Sending all processes the KILL signal... "
killall5 -9
echo "done."

# Write a reboot record to /var/log/wtmp.
halt -w

# Save the random seed between reboots.
/etc/init.d/urandom stop

echo -n "Deactivating swap... "
swapoff -a
echo "done."

echo -n "Unmounting file systems... "
umount -a
echo "done."

mount -n -o remount,ro /

################ for raid arrays #########################
# Stop all known raid arrays (except root which won't stop)
if [ -x /sbin/mdstop ]; then
echo "Stopping raid"
/sbin/mdstop -a
fi
##########################################################

# See if we need to cut the power.
if [ -x /etc/init.d/ups-monitor ]
then
/etc/init.d/ups-monitor poweroff
fi

halt -d -f
############# end halt ####################

9.2.2. /etc/init.d/reboot

#! /bin/sh
#
# reboot The commands in this script are executed as the last
# step in runlevel 6, ie reboot.
#
# Version: @(#)reboot 1.9 02-Feb-1997 [email protected]
#

PATH=/sbin:/bin:/usr/sbin:/usr/bin

############ Save raid boot and status info ##############
#
if [ -x /etc/rc.d/rc.raidown ]; then
/etc/rc.d/rc.raidown
fi
################## end raid boot #########################

# Kill all processes.
echo -n "Sending all processes the TERM signal... "
killall5 -15
echo "done."
sleep 5
echo -n "Sending all processes the KILL signal... "
killall5 -9
echo "done."

# Write a reboot record to /var/log/wtmp.
halt -w

# Save the random seed between reboots.
/etc/init.d/urandom stop

echo -n "Deactivating swap... "
swapoff -a
echo "done."

echo -n "Unmounting file systems... "
umount -a
echo "done."

mount -n -o remount,ro /

################ for raid arrays #########################
# Stop all known raid arrays (except root which won't stop)
if [ -x /sbin/mdstop ]; then
echo "Stopping raid"
/sbin/mdstop -a
fi
##########################################################

echo -n "Rebooting... "
reboot -d -f -i

10. Appendix C. - other setup files

10.1. linuxrc``linuxrc file''

10.2. loadlin -- linux.bat file - boot.par``linux.bat file -
boot.par''

10.3. linuxthreads Makefile.diff``linuxthreads Makefile.diff''

10.4. raid1.conf``raid1.conf''

10.5. raid5.conf``raid5.conf''

10.6. raidboot.conf``raidboot.conf''

10.7. rc.raidown``rc.raidown''

11. Appendix D. - obsolete linuxrc and shutdown scripts

11.1. Obsolete working - linuxrc

This linuxrc file works fine with the shutdown procedure in the next
subsection.

---------------------- linuxrc --------------------
#!/bin/sh
# ver 1.07 2-12-98
# linuxrc - for raid1 using small dos partition and loadlin
#

# mount the proc file system
/bin/mount /proc

# This may vary for your system.
# Mount the dos partitions, try both
# in case one disk is dead
/bin/mount /dosa
/bin/mount /dosc

# Set a flag in case the raid status file is not found
# then check both drives for the status file
RAIDOWN="raidstat.ro not found"
/bin/echo "Reading md0 shutdown status."
if [ -f /dosa/raidboot/raidstat.ro ]; then
RAIDOWN=`/bin/cat /dosa/raidboot/raidstat.ro`
RAIDREF=`/bin/cat /dosc/raidboot/raidgood.ref`
else
if [ -f /dosc/raidboot/raidstat.ro ]; then
RAIDOWN=`/bin/cat /dosc/raidboot/raidstat.ro`
RAIDREF=`/bin/cat /dosc/raidboot/raidgood.ref`
fi
fi

# Test for a clean shutdown with all disks operational
if [ "${RAIDOWN} != ${RAIDREF}" ]; then
echo "ERROR ${RAIDOWN}"
# Use the next 2 lines to BAIL OUT and leave rescue running
/bin/echo 0x100>/proc/sys/kernel/real-root-dev
exit # leaving the error files in dosa/raidboot,etc...
fi

# The raid array is clean, proceed by removing
# status file and writing a clean superblock
/bin/rm /dosa/raidboot/raidstat.ro
/bin/rm /dosc/raidboot/raidstat.ro
/sbin/mkraid /etc/raid1.conf -f --only-superblock

/bin/umount /dosa
/bin/umount /dosc

# Mount raid array
echo "Mounting md0, root filesystem"
/sbin/mdadd -ar

# If there are errors - BAIL OUT and leave rescue running
if [ $? -ne 0 ]; then
echo "RAID device has errors"
# Use the next 3 lines to BAIL OUT
/bin/rm /etc/mtab # remove bad mtab
/bin/echo 0x100>/proc/sys/kernel/real-root-dev
exit
fi

# else tell the kernel to switch to /dev/md0 as the /root device
# The 0x900 value the device number calculated by:
# 256*major_device_number + minor_device number
/bin/echo 0x900>/proc/sys/kernel/real-root-dev

# umount /proc to deallocate initrd device ram space
/bin/umount /proc
/bin/echo "/dev/md0 mounted as root"
exit
#------------------ end linuxrc ----------------------

11.2. Obsolete working - shutdown scripts

This shutdown procedure works fine with the preceeding linuxrc

To capture the raid array shutdown status, just before the file
systems are dismounted insert:

RAIDSTATUS=`/bin/cat /proc/mdstat | /usr/bin/grep md0`

After all the file systems are dismounted (the root file system

# root device remains mounted RO
# mount dos file systems RW
mount -n -o remount,ro /
echo "Writing RAID read-only boot FLAG(s)."
mount -n /dosa
mount -n /dosc
# create raid mounted RO flag in duplicate
# containing the shutdown status of the raid array
echo ${RAIDSTATUS} > /dosa/raidboot/raidstat.ro
echo ${RAIDSTATUS} > /dosc/raidboot/raidstat.ro

umount -n /dosa
umount -n /dosc

# Stop all the raid arrays (except root)
echo "Stopping raid"
mdstop -a

This will cleanly stop all raid devices except root. Root status is
passed to the next boot in raidstat.ro.

The complete shutdown script from my old raid1 Slackware system
follows, I have switched raid1 to the new procedure with the
/etc/raidboot.conf file.

#! /bin/sh
#
# rc.6 This file is executed by init when it goes into runlevel
# 0 (halt) or runlevel 6 (reboot). It kills all processes,
# unmounts file systems and then either halts or reboots.
#
# Version: @(#)/etc/rc.d/rc.6 1.50 1994-01-15
#
# Author: Miquel van Smoorenburg <[email protected]>
# Modified by: Patrick J. Volkerding, <[email protected]>
# Modified by: Michael A. Robinton, <[email protected]> for RAID shutdown

# Set the path.
PATH=/sbin:/etc:/bin:/usr/bin

# Set linefeed mode to avoid staircase effect.
stty onlcr

echo "Running shutdown script $0:"

# Find out how we were called.
case "$0" in
*0)
message="The system is halted."
command="halt"
;;
*6)
message="Rebooting."
command=reboot
;;
*)
echo "$0: call me as \"rc.0\" or \"rc.6\" please!"
exit 1
;;
esac

# Kill all processes.
# INIT is supposed to handle this entirely now, but this didn't always
# work correctly without this second pass at killing off the processes.
# Since INIT already notified the user that processes were being killed,
# we'll avoid echoing this info this time around.
if [ "$1" != "fast" ]; then # shutdown did not already kill all processes
killall5 -15
killall5 -9
fi

# Try to turn off quota and accounting.
if [ -x /usr/sbin/quotaoff ]
then
echo "Turning off quota."
/usr/sbin/quotaoff -a
fi
if [ -x /sbin/accton ]
then
echo "Turning off accounting."
/sbin/accton
fi

# Before unmounting file systems write a reboot or halt record to wtmp.
$command -w

# Save localtime
[ -e /usr/lib/zoneinfo/localtime ] && cp /usr/lib/zoneinfo/localtime /etc

# Asynchronously unmount any remote filesystems:
echo "Unmounting remote filesystems."
umount -a -tnfs &

# you must have issued
# 'cat /proc/mdstat | grep md0 > {your boot vol}/raidboot/raidgood.ref'
# before linuxrc will execute properly with this info
RAIDSTATUS=`/bin/cat /proc/mdstat | /usr/bin/grep md0 # capture raid status`

# Turn off swap, then unmount local file systems.
# clearing mdtab as well
echo "Turning off swap."
swapoff -a
echo "Unmounting local file systems."
umount -a -tnonfs

# Don't remount UMSDOS root volumes:
if [ ! "`mount | head -1 | cut -d ' ' -f 5`" = "umsdos" ]; then
mount -n -o remount,ro /
fi

# root device remains mounted
# mount dos file systems RW
echo "Writing RAID read-only boot FLAG(s)."
mount -n /dosa
mount -n /dosc
# create raid mounted RO flag in duplicate
# containing the shutdown status of the raid array
echo ${RAIDSTATUS} > /dosa/raidboot/raidstat.ro
echo ${RAIDSTATUS} > /dosc/raidboot/raidstat.ro

umount -n /dosa
umount -n /dosc

# Stop all the raid arrays (except root)
echo "Stopping raid"
mdstop -a

# See if this is a powerfail situation.
if [ -f /etc/power_is_failing ]; then
echo "Turning off UPS, bye."
/sbin/powerd -q
exit 1
fi

# Now halt or reboot.
echo "$message"
[ ! -f /etc/fastboot ] && echo "On the next boot fsck will be FORCED."
$command -f

12. Appendix E. - Gadi's raid stop patch for the linux kernel

--- linux/drivers/block/md.c.old Fri Nov 21 13:37:11 1997
+++ linux/drivers/block/md.c Sat Dec 6 13:34:28 1997
@@ -622,8 +622,13 @@
return do_md_run (minor, (int) arg);

case STOP_MD:
- return do_md_stop (minor, inode);
-
+ err = do_md_stop(minor, inode);
+ if (err) {
+ printk("md: enabling auto mdstop for %s\n",
kdevname(inode->i_rdev));
+ md_dev[minor].auto_mdstop = 1;
+ }
+ return err;
+
case BLKGETSIZE: /* Return device size */
if (!arg) return -EINVAL;
err=verify_area (VERIFY_WRITE, (long *) arg, sizeof(long));
@@ -692,6 +697,10 @@

sync_dev (inode->i_rdev);
md_dev[minor].busy--;
+ if (!md_dev[minor].busy && md_dev[minor].auto_mdstop) {
+ do_md_stop(minor, inode);
+ md_dev[minor].auto_mdstop = 0;
+ }
}

static int md_read (struct inode *inode, struct file *file,
--- linux/include/linux/md.h~ Fri Nov 21 13:29:14 1997
+++ linux/include/linux/md.h Fri Nov 21 13:29:14 1997
@@ -260,6 +260,7 @@
int repartition;
int busy;
int nb_dev;
+ int auto_mdstop;
void *private;
};

13. Appendix F. - rc.raidown

Copy the following text into the script file rc.raidown and save it in
/etc/rc.d.

#! /bin/sh
#
# rc.raidown This file is executed by init when it goes into runlevel
# 0 (halt) or runlevel 6 (reboot). It saves the status of
# a root mounted raid array for subsequent re-boot
#
# Version: 1.08 3-25-98 Michael A. Robinton < [email protected] >
#
############ Save raid boot and status info ##############
if [ -f /etc/raidboot.conf ]
then
{
read RaidBootDevs
read RaidStatusPath
read RaidConfigEtc
} < /etc/raidboot.conf

# you must have issued
# cat /proc/mdstat | grep md0 >
# {your boot vol mnt(s)}/{RaidStatusPath}/raidgood.ref
# before linuxrc will execute properly with this info
#
# capture raid status
RAIDSTATUS=`/bin/cat /proc/mdstat | /usr/bin/grep md0`
mkdir /tmp/raid$$
echo "Writing RAID read-only boot FLAG(s)."
for Device in ${RaidBootDevs}
do
# get mount point for raid boot device or use tmp
RBmount=$( cat /proc/mounts | /usr/bin/grep ${Device} )
if [ -n ${RBmounts} ]; then
RBmount=$( echo ${RBmount} | cut -f 2 -d ' ' )
else
RBmount="/tmp/raid$$"
mount ${Device} ${RBmount}
fi
if [ -d ${RBmount}/${RaidStatusPath} ]; then
# Create raid mounted RO flag = shutdown status of raid array
echo ${RAIDSTATUS} > ${RBmount}/${RaidStatusPath}/raidboot.ro
# Don't propagate 'fstab' from ramdisk
if [ -f /linuxrc ]; then
FSTAB=
else
FSTAB=fstab
fi
pushd /etc
# Save etc files for rescue system
/bin/tar --ignore-failed-read \
-cf ${RBmount}/${RaidStatusPath}/raidboot.etc \
raid*.conf mdtab* ${FSTAB} lilo.conf
popd
# Create new raidboot.cfg
{
/bin/echo ${RaidBootDevs}
/bin/echo ${RaidStatusPath}
/bin/echo ${RaidConfigEtc}
} > ${RBmount}/${RaidStatusPath}/raidboot.cfg
/bin/umount ${RBmount}
fi
done
rmdir /tmp/raid$$
echo "Raid boot armed"
fi
################## end raid boot #########################

14. Appendix G. - linuxrc theory of operation

This is the complex form of the linuxrc file for root mounted raid.
It must be processed with 'bash' or another shell that recognizes
shell functions.

The advantage is that it is generic and is not dependent on startup
files and parameters located in the initrd image.

A Raid_Conf parameter passed to linuxrc by the kernel at boot from
lilo or loadlin contains a pointer to the boot devices and location
the of initial 2 raidboot files needed by linuxrc (raidboot.etc and
raidboot.cfg placed by the shutdown script).

raidboot.etc containing the 'tar'ed files:

raid*
mdtab*
fstab
lilo.conf ( if applicable )

from the primary system that are transferred to the initrd
/etcetc directory at startup. With care, this file may be
edited if necessary when your system 'really' crashes.

raidboot.cfg contains the name of the boot partition in use
and applicable backup(s) as well as the path to the rest of
the raid start up file used by linuxrc. This file is
normally created by the shutdown file and may be created
manually if necessary.

raidboot.cfg is of the form, 3 lines - no comments

/dev/bootdev1 /dev/bootdev2 [/dev/bootdev3 ... and so on]
raid-status/path
name_of_raidX.conf_file

the raid-status/path does not include the name of the mount�
point

the raidX.conf filename is that one found in /etc and
normally used for ckraid and mkraid.

The following additional files reside on the permanent raid boot par�
titions. This is usually the same as above, but in emergency situa�
tions may be loaded from anywhere they are available, such as a floppy
boot disk.

� raidgood.ref created by the command cat /proc/mdstat | grep md0 >
/{raid_status_path}/raidgood.ref

See the ``shutdown scripts'' for saving this file and the next

� raidstat.ro created at each shutdown by the shutdown rc file,
saving the exit status of the raid array.

15. Appendix H. Setting up ROOT RAID on RedHat

From the [email protected] <mailto:linux-
[email protected]> mail list.

! Has anyone figured out how to do root-mounted RAID (as per
! the Root-RAID HOWTO) using RedHat? The problem is that there
! is no equivalent of Slackware's setup to install the root
! filesystem to the RAID device. All RedHat installs have to
! run from the install floppy, which makes it almost
! impossible to get at the md devices and utilities during the
! install.
!
! I think it's much easier to go out of the distribution and do it by
! hand!!

Assuming you have enough RAM (or a spare hard disk), install a minimal
system onto what will be your swap space (or onto your spare hard disk)
and/or /boot. Now do your mkraid, your mke2fs, mdrun, and mount. Next, do:

tar clf - / | tar xpfC - /mnt/raidwasmountedhere

(you may want a "v" in the second tar's flags)
Once this is done, you can set up lilo (or whatever) so that the new
raid partition is root. Then go in with RPM and/or glint (I hate
glint's behavior in the face of failed dependencies, which was fixed
but they broke it again for RH5.0 plus you can go back and forth
forever between an old and a new version of a package without
realizing the other version is installed) and install what you
really wanted.

All this assuming you couldn't sneak in at some point in the install
and do your mkraid then at the VC with the shell prompt...

! I'm building a server at the moment and I think it would be tidier
! and less likely to cause problems in the future if I start with
! glibc2, rather than move to it later.
!
! Me too.
!
! The reason I'd like to be able to use RedHat is that they
! are the only major distribution that I know of with a
! glibc2-based release.
!
! Debian works fine with me. There isn't a CD yet, but you can grab the
! distribution by ftp.

I avoided root-raid like the plague, largely because initrd is an
extra, very fragile step (having to rdev, and having lilo depend on
the bios' ID number to find the kernel's partition, are bad enough!).
However, Red Hat does have a nice mkinitrd script, needed since they
left all their SCSI drivers modular. Hack that to include your
raid utils, make sure your mdadd -ar is in the right spot in
/etc/rc.d/rc.sysinit (before any fscking) and make sure mdstop -a is
in /etc/rc.d/init.d/halt after the RO-remount of /, and go for it!

Keith [email protected] <mailto:[email protected]>