Quota mini-HOWTO
 Albert M.C. Tam [email protected]
 v0.0, 8 August 1997

 Preamble: This document is copylefted by Albert M.C. Tam
 ([email protected]).  Permission to use, copy, distribute this document
 for non-commerical purposes is hereby granted, provided that the
 author's / editor's name and this notice appear in all copies and/or
 supporting documents; that this document is not modified. This docu
 ment is distributed in 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 errors, or
 for damages results for the use of the information documented herein.
 This document describes how to enable file system quota on a Linux
 host, assigning quota for users and groups, as well as the usage of
 miscellaneous quota commands. It is intended for users running kernel
 2.x (recently tested on RedHat 4.1 running kernel 2.0.27). Users run
 ning older kernels may need to upgrade to a newer kernel version in
 order to take advantage of quota.  Feel free to send feedbacks or com
 ments to [email protected] if you find an error, or if any information is
 missing. I appreciate it.

 1.  What is Quota?


 Quota allows you to specify limits on two aspects of disk storage: the
 number of inodes a user or a group of users may possess; and the
 number of disk blocks that may be allocated to a user or a group of
 users.

 The idea behind quota is that users are forced to stay under their
 disk comsumption limit, taking away their ability to comsume unlimited
 disk space on a system. Quota is handled on a per user, per file
 system basis. If there is more than one file system which a user is
 expected to create files, then quota must be set for each file system
 seperately.

 2.  Current Status of Quota on Linux


 Quota support has been integrated into kernel since version 1.3.8x I
 heard.  Now it is part of the 2.0 release of the Linux kernel. If your
 system doesn't support quota, I really recommend an upgrade.

 Currently, quota works for ext2 type file system only.

 3.  Requirements for Using Quota on Linux


 3.1.  Kernel


 The 2.x kernel source is available from

 ______________________________________________________________________
 http://sunsite.unc.edu/pub/Linux/kernel/v2.0
 ______________________________________________________________________



 3.2.  Quota software


 Depending on the Linux distribution you have, you may, or may not have
 the quota softwares installed on your system. If you don't, then
 download the quota software source from

 ______________________________________________________________________
 ftp://ftp.funet.fi/pub/Linux/PEOPLE/Linus/subsystems/quota/all.tar.gz.
 ______________________________________________________________________



 4.  Quota Setup on Linux - Part I: The Configuration


 4.1.  Reconfigure your kernel


 Reconfigure your kernel and add quota support by typing y to:

 ______________________________________________________________________
 Quota support (CONFIG_QUOTA) [n] y
 ______________________________________________________________________



 4.2.  Compile and install the quota softwares


 The quota software source is available from

 ______________________________________________________________________
 ftp://ftp.funet.fi/pub/Linux/PEOPLE/Linus/subsystems/quota/all.tar.gz
 ______________________________________________________________________



 4.3.  time Modify your system init script to check quota and turn
 quota on at boot


 Here's an example:

 ______________________________________________________________________
 # Check quota and then turn quota on.
 if [ -x /usr/sbin/quotacheck ]
         then
                echo "Checking quotas. This may take some time."
                /usr/sbin/quotacheck -avug
                echo " Done."
         fi
          if [ -x /usr/sbin/quotaon ]
         then
                 echo "Turning on quota."
                 /usr/sbin/quotaon -avug
         fi
 ______________________________________________________________________



 The golden rule is that always turn quota on after your file systems
 in /etc/fstab have been mounted, otherwise quota will fail to work. I
 recommend turning quota on at the end of your system init script, or,
 if you like, right after the part where file systems are mounted in
 your system init script.

 4.4.  Modify /etc/fstab



 Partitions that you have not yet enabled quota normally look something
 like:

 ______________________________________________________________________
 /dev/hda1       /       ext2    defaults        1       1
 /dev/hda2       /usr    ext2    defaults        1       1
 ______________________________________________________________________



 To enable user quota support on a file system, add "usrquota" to the
 fourth field containing the word "defaults" (man fstab for details).

 ______________________________________________________________________
 /dev/hda1       /       ext2    defaults        1       1
 /dev/hda2       /usr    ext2    defaults,usrquota       1       1
 ______________________________________________________________________



 Replace "usrquota" with "grpquota", should you need group quota
 support on a file system.

 ______________________________________________________________________
 /dev/hda1       /       ext2    defaults        1       1
 /dev/hda2       /usr    ext2    defaults,grpquota       1       1
 ______________________________________________________________________



 Need both user quota and group quota support on a file system?

 ______________________________________________________________________
 /dev/hda1       /       ext2    defaults        1       1
 /dev/hda2       /usr    ext2    defaults,usrquota,grpquota       1   1
 ______________________________________________________________________



 4.5.  Create quota record "quota.user" and "quota.group"


 Both quota record files, quota.user and quota.group, should be owned
 by root, and read-write permission for root and none for anybody else.

 Login as root. Go to the root of the partition you wish to enable
 quota, then create quota.user and quota.group by doing:

 ______________________________________________________________________
 touch /partition/quota.user
 touch /partition/quota.group
 chmod 600 /partition/quota.user
 chmod 600 /partition/quota.group
 ______________________________________________________________________



 4.6.  Reboot


 Now reboot system for the changes you have made to take effect.

 Also note that subsequent partitions you wish to enable quota in the
 future only require step 4, 5, and 6.


 5.  Quota Setup on Linux - Part II: Assigning Quota for Users and
 Groups


 This operation is performed with the edquota command (man edquota for
 details).

 I would normally run quotacheck with the flags -avug to obtain the
 most updated filesystems usage prior to editing quota. This is just a
 personal habit, and not a required step however.

 5.1.  Assigning quota for a particular user


 Here's an example. I have a user with the login id bob on my system.
 The command "edquota -u bob" takes me into vi (or editor specified in
 my $EDITOR environment variable) to edit quota for user bob on each
 partition that has quota enabled:

 ______________________________________________________________________
 Quotas for user bob:
 /dev/hda2: blocks in use: 2594, limits (soft = 5000, hard = 6500)
          inodes in use: 356, limits (soft = 1000, hard = 1500)
 ______________________________________________________________________



 "blocks in use" is the total number of blocks (in kilobytes) a user
 has comsumed on a partition.

 "inodes in use" is the total number of files a user has on a
 partition.

 5.2.  Assigning quota for a particular group


 Now I have a group games on my system. "edquota -g games" takes me
 into the vi editor again to edit quota for the group games:

 ______________________________________________________________________
         Quotas for group games:
         /dev/hda4: blocks in use: 5799, limits (soft = 8000, hard = 10000)
                 inodes in use: 1454, limits (soft = 3000, hard = 4000)
 ______________________________________________________________________



 5.3.  Assigning quota for a bunch of users with the same value


 To rapidly set quotas for, say 100 users, on my system to the same
 value as my user bob, I would first edit bob's quota information by
 hand, then execute:

 ______________________________________________________________________
 edquota -p bob `awk -F: '$3 > 499 {print $1}' /etc/passwd`
 ______________________________________________________________________



 assuming that you are using csh, and that you assign your user UID's
 starting with 500.

 In addition to edquota, there are 3 terms which you should familiarize
 yourself with: Soft Limit, Hard Limit, and Grace Period.

 5.4.  Soft Limit


 _Soft limit_ indicates the maximum amount of disk usage a quota user
 has on a partition. When combined with grace period, it acts as the
 border line, which a quota user is issued warnings about his impending
 quota violation when passed.

 5.5.  Hard Limit


 Hard limit works only when grace period is set. It specifies the
 absolute limit on the disk usage, which a quota user can't go beyond
 his hard limit.

 5.6.  Grace Period


 Executed with the command "edquota -t", grace period is a time limit
 before the soft limit is enforced for a file system with quota
 enabled. Time units of sec(onds), min(utes), hour(s), day(s), week(s),
 and month(s) can be used.  This is what you'll see with the command
 "edquota -t":

 ______________________________________________________________________
 Time units may be: days, hours, minutes, or seconds
 Grace period before enforcing soft limits for users:
 /dev/hda2: block grace period: 0 days, file grace period: 0 days
 ______________________________________________________________________



 Change the 0 days part to any length of time you feel reasonable. I
 personally would choose 7 days (or 1 week).

 6.  Miscellaneous Quota Commands


 6.1.  Quotacheck


 Quotacheck is used to scan a file system for disk usages, and updates
 the quota record file "quota.user" to the most recent state. I
 recommend running quotacheck at system bootup, or via cronjob
 periodically (say, every week?).

 6.2.  Repquota


 Repquota produces a summarized quota information for a file system.
 Here is a sample output repquota gives:

 ______________________________________________________________________
 # repquota -a
                                 Block limits               File limits
         User            used    soft    hard  grace    used  soft  hard  grace
         root      --  175419       0       0          14679     0     0
         bin       --   18000       0       0            735     0     0
         uucp      --     729       0       0             23     0     0
         man       --      57       0       0             10     0     0
         user1     --   13046   15360   19200            806  1500  2250
         user2     --    2838    5120    6400            377  1000  1500
 ______________________________________________________________________



 6.3.  Quotaon and Quotaoff


 Quotaon is used to turn on quota accouting; quotaoff to turn it off.
 Actually both files are similar. They are executed at system startup
 and shutdown.

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