Chapter 24. Limiting storage space usage on ext4 with quotas

Procedure

1. Enable quotas on file system creation:

   # mkfs.ext4 -O quota /dev/sda

   Note

   Only user and group quotas are enabled and initialized by default.

2. Change the defaults on file system creation:

   # mkfs.ext4 -O quota -E quotatype=usrquota:grpquota:prjquota /dev/sda

3. Mount the file system:

   # mount /dev/sda

Procedure

1. Unmount the file system:

   # umount /dev/sda

2. Enable quotas on existing file system:

   # tune2fs -O quota /dev/sda

   Note

   Only user and group quotas are initialized by default.

3. Change the defaults:

   # tune2fs -Q usrquota,grpquota,prjquota /dev/sda

4. Mount the file system:

   # mount /dev/sda

Procedure

1. Assign the quota for a user:

   # edquota username

   Replace username with the user to which you want to assign the quotas.

   For example, if you enable a quota for the /dev/sda partition and execute the command edquota testuser, the following is displayed in the default editor configured on the system:

   Disk quotas for user testuser (uid 501):
   Filesystem   blocks   soft   hard   inodes   soft   hard
   /dev/sda      44043      0      0    37418      0      0

2. Change the desired limits.

   If any of the values are set to 0, limit is not set. Change them in the text editor.

   For example, the following shows the soft and hard block limits for the testuser have been set to 50000 and 55000 respectively.

   Disk quotas for user testuser (uid 501):
   Filesystem   blocks   soft   hard   inodes   soft   hard
   /dev/sda      44043  50000  55000    37418      0      0

   • The first column is the name of the file system that has a quota enabled for it.
   • The second column shows how many blocks the user is currently using.
   • The next two columns are used to set soft and hard block limits for the user on the file system.
   • The inodes column shows how many inodes the user is currently using.

   • The last two columns are used to set the soft and hard inode limits for the user on the file system.

     • The hard block limit is the absolute maximum amount of disk space that a user or group can use. Once this limit is reached, no further disk space can be used.
     • The soft block limit defines the maximum amount of disk space that can be used. However, unlike the hard limit, the soft limit can be exceeded for a certain amount of time. That time is known as the grace period. The grace period can be expressed in seconds, minutes, hours, days, weeks, or months.

Procedure

1. Set a group quota:

   # edquota -g groupname

   For example, to set a group quota for the devel group:

   # edquota -g devel

   This command displays the existing quota for the group in the text editor:

   Disk quotas for group devel (gid 505):
   Filesystem   blocks  soft  hard  inodes  soft  hard
   /dev/sda     440400     0     0   37418     0     0

2. Modify the limits and save the file.

Procedure

1. Add the project-controlled directories to /etc/projects. For example, the following adds the /var/log path with a unique ID of 11 to /etc/projects. Your project ID can be any numerical value mapped to your project.

   # echo 11:/var/log >> /etc/projects

2. Add project names to /etc/projid to map project IDs to project names. For example, the following associates a project called Logs with the project ID of 11 as defined in the previous step.

   # echo Logs:11 >> /etc/projid

3. Set the desired limits:

   # edquota -P 11

   Note

   You can choose the project either by its project ID (11 in this case), or by its name (Logs in this case).

4. Using quotaon, enable quota enforcement:

   See Enabling quota enforcement.

Procedure

1. Run the repquota command:

   # repquota

   For example, the command repquota /dev/sda produces this output:

   *** Report for user quotas on device /dev/sda
   Block grace time: 7days; Inode grace time: 7days
   			Block limits			File limits
   User		used	soft	hard	grace	used	soft	hard	grace
   ----------------------------------------------------------------------
   root      --      36       0       0              4     0     0
   kristin   --     540       0       0            125     0     0
   testuser  --  440400  500000  550000          37418     0     0

2. View the disk usage report for all quota-enabled file systems:

   # repquota -augP

   The -- symbol displayed after each user determines whether the block or inode limits have been exceeded. If either soft limit is exceeded, a + character appears in place of the corresponding - character. The first - character represents the block limit, and the second represents the inode limit.

   The grace columns are normally blank. If a soft limit has been exceeded, the column contains a time specification equal to the amount of time remaining on the grace period. If the grace period has expired, none appears in its place.

   For more information, see the repquota(8) man page for more information.