Disk Quota
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From Wikipedia:
- "A disk quota is a limit set by a system administrator that restricts certain aspects of file system usage on modern operating systems. The function of setting quotas to disks is to allocate limited disk-space in a reasonable way."
This article covers the installation and setup of disk quota.
Contents |
Installing
Disk quota only requires one package:
# pacman -S quota-tools
Enabling
For journaled quota, see the notes in #Journaled quota.
1. First, edit /etc/fstab to enable the quota mount option(s) on selected file systems:
/dev/sda1 /home ext4 defaults 1 1
- edit it as follows;
/dev/sda1 /home ext4 defaults,usrquota 1 1
- or aditionally enable the group quota mount option;
/dev/sda1 /home ext4 defaults,usrquota,grpquota 1 1
2. Create the quota files in the file system:
# touch /home/aquota.user # touch /home/aquota.group # For group quota
2. The next step is to remount:
# mount -vo remount /home
4. Create the quota index:
# quotacheck -vgum /home
- or for all partitions with the quota mount options in /etc/mtab;
# quotacheck -vguma
5. Finally, enable quotas:
# quotaon -av
Journaled quota
Enabling journaling for disk quota adds the same benefits journaled file systems do for forced shutdowns, meaning that data is less likely to become corrupt.
Setting up journaled quota is the same as above, except for the mount options:
/dev/sda1 /home ext4 defaults,usrjquota=aquota.user,jqfmt=vfsv0 1 1
or aditionally enable the group quota mount option;
/dev/sda1 /home ext4 defaults,usrjquota=aquota.user,grpjquota=aquota.grp,jqfmt=vfsv0 1 1
Configuring
Replace $USER as appropriate and edit the quota as root:
Disk quotas for user $USER (uid 1000): Filesystem blocks soft hard inodes soft hard /dev/sda1 1944 0 0 120 0 0
- blocks
- 1k blocks
- inodes
- Number of entries in directory file
- soft
- Max number of blocks/inodes user may have on partition before warning is issued and grace period countdown begins. If set to "0" (zero) then no limit is enforced.
- hard
- Max number of blocks/inodes user may have on partition. If set to "0" (zero) then no limit is enforced.
Example setup
Editing the limits as below, for example:
Disk quotas for user testuser (uid 1000): Filesystem blocks soft hard inodes soft hard /dev/sda1 695879 10000 15000 6741 0 0
sets the following restrictions: the soft limit means that once testuser uses over 10MB of space a warning email gets ensued, and after a period of time the soft limit gets enforced. The hard limit is stricter, so to speak; a user cannot go over this limit.
To alter the soft limit grace period:
# edquota -t
Managing
Checking for quota limits and advanced operations
Basics
Use this command to check for quotas on a specific partition:
# repquota /home
Use this command to check for all quotas that apply to a user:
# quota -u $USER
for groups;
# quota -g $GROUP
Copying quota settings
The idea is to make a temporary user acount, modify the quota settings for that user, and then copy the generated quota files for all users to use. After setting quota settings for quotauser, copy the settings:
# edquota -p quotauser `awk -F: '$3 > 999 {print $1}' /etc/passwd`
This applies the settings to users with a UID equal to or greater than 1000.
Other commands
There are several useful commands:
repquota -a # Shows the status on diskusage warnquota # Can be used to warn the users about their quota setquota # Non-interactive quota setting--useful for scripting
Lasty, quotastats is used to give thorough information about the quota system:
Number of dquot lookups: 101289 Number of dquot drops: 101271 Number of still active inodes with quota : 18 Number of dquot reads: 93 Number of dquot writes: 2077 Number of quotafile syncs: 134518740 Number of dquot cache hits: 7391 Number of allocated dquots: 90 Number of free dquots: 2036 Number of in use dquot entries (user/group): -1946