Disk quotas can be configured for individual users as well as user groups.
This kind of flexibility makes it possible to give each user a small quota
to handle "personal" file (such as email and reports), while allowing
the projects they work on to have more sizable quotas (assuming the
projects are given their own groups).
In addition, quotas can be set not just to control the number of disk
blocks consumed but to control the number of inodes. Because inodes
are used to contain file-related information, this allows control over the
number of files that can be created.
6.1. Configuring Disk Quotas
To implement disk quotas, use the following steps:
Enable quotas per file system by modifying
/etc/fstab
Remount the file system(s)
Create the quota files and generate the disk usage
table
Assign quotas
Each of these steps is discussed in detail in the following sections.
6.1.1. Enabling Quotas
As root, using the text editor of your choice, add the
usrquota and/or grpquota options
to the file systems that require quotas:
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
none /dev/pts devpts gid=5,mode=620 0 0
LABEL=/home /home ext3 defaults,usrquota,grpquota 1 2
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hda2 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0 |
In this example, the /home file system has both
user and group quotas enabled.
6.1.2. Remounting the File Systems
After adding the userquota and
grpquota options, remount each file system whose
fstab entry has been modified. If the file
system is not in use by any process, use the umount
command followed by the mount to remount the file
system. If the file system is currently in use, the easiest method
for remounting the file system is to reboot the system.
6.1.3. Creating Quota Files
After each quota-enabled file system is remounted, the system is now
capable of working with disk quotas. However, the file system itself
is not yet ready to support quotas. The next step is to run the
quotacheck command.
The quotacheck command examines quota-enabled file
systems and builds a table of the current disk usage per file system.
The table is then used to update the operating system's copy of disk
usage. In addition, the file system's disk quota files are updated.
To create the quota files (aquota.user and
aquota.group) on the file system, use the
-c option of the quotacheck
command. For example, if user and group quotas are enabled for the
/home partition, create the files in the
/home directory:
The -a option means that all mounted non-NFS file
systems in /etc/mtab are checked to see if
quotas are enabled. The -c option specifies that
the quota files should be created for each file system with quotas
enabled, the -u specifies to check for user quotas,
and the -g option specifies to check for group
quotas.
If neither the -u or -g options are
specified, only the user quota file is created. If only
-g is specified, only the group quota file is created.
After the files are created, run the following command to generate the
table of current disk usage per file system with quotas enabled:
The options used are as follows:
a — Check all quota-enabled,
locally-mounted file systems
v — Display verbose status information
as the quota check proceeds
u — Check user disk quota information
g — Check group disk quota information
After quotacheck has finished running, the quota
files corresponding to the enabled quotas (user and/or group) are
populated with data for each quota-enabled file system such as
/home.
6.1.4. Assigning Quotas per User
The last step is assigning the disk quotas with the
edquota command.
To configure the quota for a user, as root in a shell prompt, execute
the command:
Perform this step for each user for which you want to implement a
quota. For example, if a quota is enabled in
/etc/fstab for the /home
partition (/dev/hda3) and the command
edquota testuser is executed, the following is
shown in the editor configured as the default for the system:
Disk quotas for user testuser (uid 501):
Filesystem blocks soft hard inodes soft hard
/dev/hda3 440436 0 0 37418 0 0 |
 | Note |
|---|
| | The text editor defined by the EDITOR environment
variable is used by edquota. To change the editor,
set the EDITOR environment variable to the full path of
the editor of your choice.
|
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.
A hard 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 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.
If any of the values are set to 0, that limit is not set. In the
text editor, change the desired limits. For example:
Disk quotas for user testuser (uid 501):
Filesystem blocks soft hard inodes soft hard
/dev/hda3 440436 500000 550000 37418 0 0 |
To verify that the quota for the user has been set, use the command:
6.1.5. Assigning Quotas per Group
Quotas can also be assigned on a per-group basis. For example, to set
a group quota for the devel group,
use the command (the group must exist prior to setting the group
quota):
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/hda3 440400 0 0 37418 0 0 |
Modify the limits, save the file, and then configure the quota.
To verify that the group quota has been set, use the command:
6.1.6. Assigning Quotas per File System
To assign quotas based on each file system enabled for quotas, use the command:
Like the other edquota commands, this one opens the
current quotas for the file system in the text editor:
Grace period before enforcing soft limits for users:
Time units may be: days, hours, minutes, or seconds
Filesystem Block grace period Inode grace period
/dev/hda3 7days 7days |
Change the block grace period or inode grace period, save the
changes to the file, and exit the text editor.
