Disk QuotasContributed by &a.mpp;. 26 February
1996Quotas are an optional feature of the operating system that allow you
to limit the amount of disk space and/or the number of files a user, or
members of a group, may allocate on a per-file system basis. This is used
most often on timesharing systems where it is desirable to limit the
amount of resources any one user or group of users may allocate. This
will prevent one user from consuming all of the available disk
space.Configuring Your System to Enable Disk QuotasBefore attempting to use disk quotas it is necessary to make sure
that quotas are configured in your kernel. This is done by adding the
following line to your kernel configuration file:
options QUOTAThe stock GENERIC kernel does not have this
enabled by default, so you will have to configure, build and install a
custom kernel in order to use disk quotas. Please refer to the Configuring the FreeBSD Kernel section
for more information on kernel configuration.Next you will need to enable disk quotas in
/etc/sysconfig. This is done by changing the line:
quotas=NO
to:
quotas=YESIf you are running FreeBSD 2.2.2 or later, the configuration file
will be /etc/rc.conf instead and the variable name
changed to:
check_quotas=YESFinally you will need to edit /etc/fstab to
enable disk quotas on a per-file system basis. This is where you can
either enable user or group quotas or both for all of your file
systems.To enable per-user quotas on a file system, add the
userquota option to the options field in the
/etc/fstab entry for the file system you want to to
enable quotas on. For example:
/dev/da1s2g /home ufs rw,userquota 1 2Similarly, to enable group quotas, use the
groupquota option instead of the
userquota keyword. To enable both user and group
quotas, change the entry as follows:
/dev/da1s2g /home ufs rw,userquota,groupquota 1 2By default the quota files are stored in the root directory of the
file system with the names quota.user and
quota.group for user and group quotas respectively.
See man fstab for more information. Even though that
man page says that you can specify an alternate location for the quota
files, this is not recommended since all of the various quota utilities
do not seem to handle this properly.At this point you should reboot your system with your new kernel.
/etc/rc will automatically run the appropriate
commands to create the initial quota files for all of the quotas you
enabled in /etc/fstab, so there is no need to
manually create any zero length quota files.In the normal course of operations you should not be required to run
the quotacheck, quotaon, or
quotaoff commands manually. However, you may want to
read their man pages just to be familiar with their operation.Setting Quota LimitsOnce you have configured your system to enable quotas, verify that
they really are enabled. An easy way to do this is to run&prompt.root; quota -vYou should see a one line summary of disk usage and current quota
limits for each file system that quotas are enabled on.You are now ready to start assigning quota limits with the
edquota command.You have several options on how to enforce limits on the amount of
disk space a user or group may allocate, and how many files they may
create. You may limit allocations based on disk space (block quotas) or
number of files (inode quotas) or a combination of both. Each of these
limits are further broken down into two categories: hard and soft
limits.A hard limit may not be exceeded. Once a user reaches their hard
limit they may not make any further allocations on the file system in
question. For example, if the user has a hard limit of 500 blocks on a
file system and is currently using 490 blocks, the user can only
allocate an additional 10 blocks. Attempting to allocate an additional
11 blocks will fail.Soft limits on the other hand can be exceeded for a limited amount
of time. This period of time is known as the grace period, which is one
week by default. If a user stays over his or her soft limit longer than
their grace period, the soft limit will turn into a hard limit and no
further allocations will be allowed. When the user drops back below the
soft limit, the grace period will be reset.The following is an example of what you might see when you run
then edquota command. When the
edquota command is invoked, you are placed into the
editor specified by the EDITOR environment variable, or
in the vi editor if the EDITOR
variable is not set, to allow you to edit the quota limits.&prompt.root; edquota -u test
Quotas for user test:
/usr: blocks in use: 65, limits (soft = 50, hard = 75)
inodes in use: 7, limits (soft = 50, hard = 60)
/usr/var: blocks in use: 0, limits (soft = 50, hard = 75)
inodes in use: 0, limits (soft = 50, hard = 60)You will normally see two lines for each file system that has quotas
enabled. One line for the block limits, and one line for inode limits.
Simply change the value you want updated to modify the quota limit. For
example, to raise this users block limit from a soft limit of 50 and a
hard limit of 75 to a soft limit of 500 and a hard limit of 600, change:
/usr: blocks in use: 65, limits (soft = 50, hard =
75) to: /usr: blocks in use: 65,
limits (soft = 500, hard = 600)The new quota limits will be in place when you exit the
editor.Sometimes it is desirable to set quota limits on a range of uids.
This can be done by use of the option on the
edquota command. First, assign the desired quota
limit to a user, and then run edquota -p protouser
startuid-enduid. For example, if user
test has the desired quota limits, the following
command can be used to duplicate those quota limits for uids 10,000
through 19,999:&prompt.root; edquota -p test 10000-19999The ability to specify uid ranges was added to the system after 2.1
was released. If you need this feature on a 2.1 system, you will need
to obtain a newer copy of edquota.See man edquota for more detailed
information.Checking Quota Limits and Disk UsageYou can use either the quota or the
repquota commands to check quota limits and disk
usage. The quota command can be used to check
individual user and group quotas and disk usage. Only the super-user
may examine quotas and usage for other users, or for groups that they
are not a member of. The repquota command can be
used to get a summary of all quotas and disk usage for file systems with
quotas enabled.The following is some sample output from the quota
-v command for a user that has quota limits on two file
systems.
Disk quotas for user test (uid 1002):
Filesystem blocks quota limit grace files quota limit grace
/usr 65* 50 75 5days 7 50 60
/usr/var 0 50 75 0 50 60On the /usr file system in the above example
this user is currently 15 blocks over their soft limit of 50 blocks and
has 5 days of their grace period left. Note the asterisk
* which indicates that the user is currently over
their quota limit.Normally file systems that the user is not using any disk space on
will not show up in the output from the quota
command, even if they have a quota limit assigned for that file system.
The option will display those file systems, such as
the /usr/var file system in the above
example.* Quotas over NFSThis section is still under development.