HARD DISK UPGRADE MINI HOW-TO
Yves Bellefeuille,
[email protected]
Version 1.0,
31 January 1998
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_How to copy a Linux system from one hard disk to another._
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1. Install both disks on your system
2. Unmount non-Linux partitions
3. Partition the new disk
4. Format the new disk
5. Mount the new disk
6. Copy the files from the old disk to the new disk
7. Modify /etc/fstab as appropriate
8. Prepare LILO to boot the new disk
9. Remove the old disk
10. Reboot the system, install LILO on the new disk
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Recently, I replaced my small 249 Mb hard disk with a larger disk. I
wanted to transfer my entire Linux system, including LILO, from the
old disk to the new disk. This is how I did it.
In the following explanation, I use "/dev/hda" to denote the "old"
disk, and "/dev/hda1" means the old Linux partition. "/dev/hdb" means
the "new" disk, and "/dev/hdb1" means the new Linux partition.
Therefore, I'm assuming that Linux is on the first partition of the
first disk. Modify this as appropriate for your set-up.
This document is based on my own system, running Red Hat 4.2, and I've
tested all the commands that follow with that distribution. I've also
tested them under Debian 1.3.1 and Slackware 3.3, and I indicate a few
differences to note if you're using those distributions.
If the commands don't work properly on your system, please let me
know, telling me what version of Linux you're using.
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1. Install both disks on your system
Modern systems can accept four "EIDE" devices on the hard disk
controller, so there shouldn't be any problem installing both disks on
your system at the same time, even if you also have other EIDE
devices. Hard disks and CD-ROM drives are typical EIDE devices. Floppy
drives and tape drives are usually connected to the floppy drive
controller rather than to the hard disk controller.
SCSI adapters are even more flexible and can accept seven devices. If
you're lucky (and rich) enough to have a SCSI adapter, you probably
already know this, and you probably know which of your devices are
SCSI devices! For more information, see the SCSI How-To.
Even the oldest systems can accept two devices on the hard disk
controller, so you can still install both hard disks at the same time.
However, if you already have another device installed in addition to
your hard disk (for example, if you have both a hard disk and a CD-ROM
drive), you'll have to remove the other device to be able to install
the old hard disk and the new hard disk at the same time.
You must configure the disks as "master" or "slave" by installing the
disks' jumpers as appropriate. You'll often find configuration
information on the disks themselves; if not, consult the manuals or
the disks' manufacturers.
You must also inform the BIOS of the disks' presence and of their
"geometry". Usually, you enter the BIOS setup programme by pressing a
key during the system boot-up. Here's what to do for some common
BIOSes:
American Megatrends (AMI): Del key during Power-On Self-Test (POST)
Award: Ctrl-Alt-Esc
Compaq: F10 key after the square appears in the top right corner of
the screen during boot-up
Dell: Ctrl-Alt-Enter
DTK: Esc key during Power-On Self-Test
IBM PS/2: Ctrl-Alt-Del, then Ctrl-Alt-Ins when the cursor is in the
top right corner
Phoenix: Ctrl-Alt-Esc, or Ctrl-Alt-S, or Ctrl-Alt-Enter
Many older systems require an Installation or Reference Disk.
(I'm interested in receiving information on other BIOSes to add them
to this list.)
Reboot the system and login as root.
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2. Unmount non-Linux partitions
Some people like to mount partitions from other operating systems
(DOS, Windows, OS/2, etc.) so they can use them under Linux. These
partitions must be created and copied under their own operating
system, and you should unmount them before copying your Linux
partition. For example, if you have a DOS partition mounted at /dos,
you must unmount it with this command:
umount /dos
Note that the command is "umount", with the first letter "n" missing
from the word "unmount".
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3. Partition the new disk
Use this command to partition the new disk:
fdisk /dev/hdb
For more information on partitioning, see the Installation How-To and
the Partitioning Mini How-To.
If your new disk has over 1024 cylinders, see the Large Disk Mini
How-To. In brief, you should install all files required to boot Linux
within the first 1024 cylinders. One way to do this is to create a
small partition (1 Mb or 2 Mb) just for the /boot directory at the
beginning of the disk. (_Slackware only:_ The kernel is at /vmlinuz
rather than /boot/vmlinuz, so you should put both the / directory and
the /boot directory in this partition.)
Partitions for systems other than Linux should be created using their
own fdisk or equivalent command rather than with Linux's fdisk.
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4. Format the new disk
Use the following command to format the new disk:
mkfs.ext2 /dev/hdb1
To check the disk for bad blocks (physical defects), add the -c option
just before "/dev/hdb1".
(Note: Contrary to what the man page states, the command "mkfs -t ext2
-c /dev/hdb1" doesn't check for bad blocks under any of Red Hat,
Debian or Slackware.)
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5. Mount the new disk
Create a directory where you'll mount the new disk, for example
/new-disk, and mount it there:
mkdir /new-disk
mount -t ext2 /dev/hdb1 /new-disk
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6. Copy the files from the old disk to the new disk
You want to completely reproduce the disk structure, including links.
However, you _don't_ want to copy the directory /new-disk, since this
would copy the new disk to itself!
Furthermore, you want to create the /proc directory on the new disk,
but you don't want to copy its contents: /proc is a "virtual" file
system and doesn't have any actual files, but rather contains
information on the processes running on the system.
Here are four different ways to copy the old disk to the new one. This
may take quite a while, especially if you have a large disk or little
memory. You can expect to be able to copy 10 Mb per minute, and
possibly much more.
You can follow the copy's progress by using the command "df" from
another terminal. If you're as easily amused as I am, try "watch df"
or "watch ls -l /new-disk" to see a report updated every two seconds;
press Ctrl-C to end the display. Be aware that running the "watch"
programme itself will slow down the copying.
1. cp -ax / /new-disk
This is the simplest method, but will only work if your original
Linux system is on a single disk partition. The -a option preserves
the original system as much as possible. The -x option limits cp to
a single file system; this is necessary to avoid copying the
/new-disk and /proc directories.
2. cd / && cp -a `/bin/ls -1A | egrep -v "^new-disk$|^proc$"`
/new-disk
(Write this all on one line.)
This goes to the root directory and then copies all files and
directories except /new-disk and /proc to /new-disk. Note that the
first option after ls is the number 1, not the letter L!
This command should work in all circumstances.
3. (cd / && tar cpf - . --exclude new-disk --exclude proc) | (cd
/new-disk && tar xpf -)
(Write this all on one line.)
This goes to the root directory, "tars" everything except /new-disk
and /proc, switches to /new-disk and "untars" everything there. Note
that there must not be a slash before or after the names of the
directories in the --exclude options.
(Note: The option -l doesn't work here, since tar will still
re-create the directories /new-disk and /proc even though it doesn't
copy their contents. Therefore, tar's -l option doesn't have the
same behaviour as cp's -x option.)
This method is somewhat slower than the others.
4. cp -a /bin /boot /dev /etc /home /lib /lost+found /mnt /root /sbin
/tmp /usr /var /new-disk
(Write this all on one line.)
The last directory, /new-disk, is the destination for the cp
command. All the other directories are the sources. Therefore, here
I'm copying all the directories I'm listing to /new-disk.
With this method, you simply list yourself the directories you want
to copy. Here I listed all my directories except /new-disk and
/proc. If you can't use the other methods for any reason, you can
always use this command to manually specify the directories you want
to copy.
With this method only, if there are any files in the root directory
itself, you need another command to copy them. In particular, this
is required with Debian and Slackware, since these distributions put
files in the root directory:
cp -dp /* /.* /new-disk
After using any of these four methods, you must also create the /proc
directory on the new disk:
mkdir /new-disk/proc
At this point, you may verify the file structure on the new disk, if
you wish:
umount /new-disk
fsck.ext2 -f /dev/hdb1
mount -t ext2 /dev/hdb1 /new-disk
You may also use the following script to compare the two disks, to
ensure that the files were copied properly:
#!/bin/sh
cd /
for file in `/bin/ls -1A | egrep -v '^new-disk$|^proc$'`
do
find $file -xtype f -exec cmp \{\} /new-disk/\{\} \;
done
(_Slackware only:_ A basic Slackware installation doesn't include the
"cmp" or "diff" commands, so you won't be able to run this script if
you have only installed the basic files.)
This will only compare regular files, not character or block special
files (in the /dev directory), sockets, etc., since the "cmp" command
doesn't work properly with these. I would welcome suggestions on how
to verify these "special" files.
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7. Modify /etc/fstab as appropriate
If your new disk doesn't have the same partitions or organization as
the old disk, modify the file /etc/fstab on the new disk as
appropriate. Remember that this file is currently located at
/new-disk/etc/fstab.
Make sure that the disk partitions in the first column correspond to
the organization you'll have with the new disk, once the old disk has
been removed, and that you're only mounting one partition at "/" as
shown in the second column.
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8. Prepare LILO to boot the new disk
This is the most complicated step. I'm assuming that LILO is installed
on the hard disk's Master Boot Record (MBR); this seems to be the most
common configuration.
You want to install LILO on what's presently the second hard disk.
It's clear that LILO can't _run_ from the second hard disk; however,
LILO's documentation does anticipate that you might want to _install_
LILO on the second hard disk, for example if the first hard disk will
be removed:
LILO can't be stored at any of the following locations:
- on the second hard disk. (Unless for backup purposes, if the
current first disk will be removed or disabled, or if some other
boot loader is used, that is capable of loading boot sectors from
other drives.)
However, the documentation doesn't explain the proper way to install
LILO on the second hard disk if the first hard disk will be removed,
and I've concluded after many attempts that it isn't possible to
install LILO directly onto the MBR of the second hard disk and have it
work correctly the first time.
Instead, I suggest the use of a boot diskette to boot the new hard
disk the first time.
Insert an empty diskette, format it, create a file system on it and
mount it:
fdformat /dev/fd0H1440
mkfs.ext2 /dev/fd0
mount -t ext2 /dev/fd0 /mnt
(_Debian only:_ The command "fdformat" is not included in a basic
installation with Debian. If you don't have this command, you may omit
it if the floppy is already formatted. In this case, you should check
the diskette for bad blocks by adding "-c" after the "mkfs.ext2"
command.
(_Debian and Slackware only:_ Use the command "fdformat
/dev/fd0h1440", with a lower case "h".)
Copy all files in /boot to the diskette:
cp -dp /boot/* /mnt
(_Slackware only:_ Copy the file /vmlinuz to the boot diskette; use
the command "cp /vmlinuz /mnt".)
Create a new file /mnt/lilo.conf as follows:
boot=/dev/fd0 # Install LILO on floppy disk.
map=/mnt/map # Location of "map file".
install=/mnt/boot.b # File to copy to floppy's boot sector.
prompt # Have LILO show "LILO boot:" prompt.
timeout=50 # Boot default system after 5 seconds.
# (Value is in tenths of seconds.)
image=/mnt/vmlinuz # Location of Linux kernel on floppy.
label=linux # Label for Linux system.
root=/dev/hda1 # Location of root partition on new hard
# disk. Modify this as appropriate for
# your system.
# Note that you must use the name of the
# future location, once the old disk has
# been removed.
(_Debian only:_ In the "image" line, use the actual name of the Linux
kernel. For example, with Debian 1.3.1, use "/mnt/vmlinuz-2.0.29".)
Install LILO on the boot diskette:
/sbin/lilo -C /mnt/lilo.conf
The -C option tells /sbin/lilo what configuration file to use.
Unmount the diskette:
umount /mnt
and shut down the system.
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9. Remove the old disk
After removing the old disk, remember to modify the disk jumpers and
the BIOS information to reflect the changes.
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10. Reboot the system, install LILO on the new disk
Reboot the system from the boot diskette you just made. To do so, you
may have to modify your BIOS's boot-up sequence to "A:, C:".
Make any necessary changes to the /etc/lilo.conf file, and run
/sbin/lilo to install LILO on the new disk. With Debian, make sure
that the "boot" line says "/dev/hda" rather than "/dev/hda1" or
similar if you want to install LILO on the Master Boot Record.
You can then try re-booting your system from your new hard disk to
test if everything is working properly. If you run into any problems,
you can still use the diskette you just made to boot your system.
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Acknowledgements
Special thanks to _Dr Konrad Hinsen_ of the Institut de biologie
structurale, Grenoble, France, who has been kindly acting as my
personal Linux guru. Thanks also to _Frank Damgaard_, _Paul Koning_
and _Josh Rabinowitz_, and to _Scott Christensen_ for alerting me to
some particularities of the Slackware distribution.
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