Chapter 58 Managing Quotas (Tasks)

This chapter describes how to set up and administer quotas for disk space and inodes. This is a list of the step-by-step instructions in this chapter.

• "How to Configure File Systems for Quotas"

• "How to Set Up Quotas for a User"

• "How to Set Up Quotas for Multiple Users"

• "How to Check Quota Consistency"

• "How to Turn Quotas On"

• "How to Check for Exceeded Quotas"

• "How to Check Quotas on a File System"

• "How to Change the Soft Time Limit Default"

• "How to Change Quotas for a User"

• "How to Disable Quotas for a User"

• "How to Turn Quotas Off"

Using Quotas

Using quotas enable system administrators to control the size of UFS file systems by limiting the amount of disk space and the number of inodes (which roughly corresponds to the number of files) that individual users can acquire. For this reason, quotas are especially useful on the file systems where user home directories reside.

Once they are in place, quotas can be changed to adjust the amount of disk space or number of inodes that users can consume. Additionally, quotas can be added or removed as system needs change. See "Changing and Removing Quotas" for instructions on changing quotas or the amount of time that quotas can be exceeded, disabling individual quotas, or removing quotas from file systems.

In addition, quota status can be monitored. Quota commands enable administrators to display information about quotas on a file system, or search for users who have exceeded their quotas. For procedures that describe how to use these commands, see "Checking Quotas".

Soft Limits vs. Hard Limits

You can set both soft and hard limits. The system will not allow a user to exceed his or her hard limit. However, a system administrator may set a soft limit (sometimes referred to as a quota) which can be temporarily exceeded by the user. The soft limit must be less than the hard limit.

Once the user exceeds the soft limit a timer begins. While the timer is ticking, the user is allowed to operate above the soft limit but cannot exceed the hard limit. Once the user goes below the soft limit, the timer gets reset. However, if the user's usage remains above the soft limit when the timer expires, the soft limit is enforced as a hard limit. By default, the soft limit timer is seven days.

The value of the timer is shown by the timeleft field in the repquota and quota commands.

For example, let's say a user has a soft limit of 10,000 blocks and a hard limit of 12,000 blocks. If the user's block usage exceeds 10,000 blocks and the timer is also exceeded (more than seven days), the user will not be able to allocate more disk blocks on that file system until his or her usage drops below the soft limit.

Difference Between Disk Block and File Limits

There are two resources that a file system provides to the user: blocks (for data) and inodes (for files). Each file consumes one inode. File data is stored in data blocks (usually made of up 1 kilobyte blocks.)

Assuming there are no directories, it is possible for a user to exceed his or her inode quota without using any blocks by creating all empty files. It is also possible for a user to use only one inode yet exceed his or her block quota by simply creating one file large enough to consume all the data blocks in the user's quota.

Setting Up Quotas

You can set up quotas to limit the amount of disk space and number of inodes (roughly equivalent to the number of files) available to users. These quotas are activated automatically each time a file system is mounted. This section describes how to configure file systems for quotas, and how to set up and activate quotas.

Setting up quotas involves these general steps:

1. A series of commands prepares a file system to accept quotas, ensuring that quotas will be enforced each time the system is rebooted and the file system is mounted. Entries must be added to the /etc/vfstab file, and a quotas file must be created in the top-level directory of the file system.

2. After a quota is created for one user, it can be copied as a prototype to set up other user quotas.

3. Before quotas are actually turned on, another command checks for consistency by comparing the proposed quotas with the current disk usage to make sure that there are no conflicts.

4. Finally, a command turns the quotas on for one or more entire file systems.

These steps ensure that quotas are automatically activated on a file system each time it is mounted. For specific information about these procedures, see "Setting Up Quotas Task Map"

Table 58-1 describes the commands you use to set up disk quotas.

Guidelines for Setting Up Quotas

Before you set up quotas, you need to determine how much space and how many inodes to allocate to each user. If you want to be sure the total file system space is never exceeded, you can divide the total size of the file system between the number of users. For example, if three users share a 100-Mbyte slice and have equal disk space needs, you could allocate 33 Mbytes to each. In environments where not all users are likely to push their limits, you may want to set individual quotas so that they add up to more than the total size of the file system. For example, if three users share a 100-Mbyte slice, you could allocate 40 Mbytes to each.

When you have established a quota for one user by using the edquota command, you can use this quota as a prototype to set the same quota for other users on the same file system.

After you have configured UFS file systems for quotas and established quotas for each user, run the quotacheck command to check consistency between current disk usage and quota files before you actually turn quotas on. Also, if systems are rebooted infrequently, it is a good idea to periodically run quotacheck.

The quotas you set up with edquota are not enforced until you turn them on by using the quotaon command. If you have properly configured the quota files, quotas will be turned on automatically each time a system is rebooted and the file system is mounted.

Setting Up Quotas Task Map

How to Configure File Systems for Quotas

1. Become superuser.

2. Edit the /etc/vfstab file by using the editor of your choice. Add rq to the mount options field for each UFS file system that will have quotas.

3. Exit the file, saving the changes.

4. Change directory to the top of the file system that will have quotas.

5. Create a file named quotas.

   # touch quotas

6. Change permissions to read/write for root only.

   # chmod 600 quotas

Examples--Configuring File Systems for Quotas

The following example from /etc/vfstab shows that the /export/home directory from the system pluto is mounted as an NFS file system on the local system with quotas enabled.

#device          device   mount       FS    fsck   mount   mount
#to mount         to fsck  point       type  pass   at boot options
#
pluto:/export/home -       /export/home nfs    -     yes    rq

The following example line from /etc/vfstab shows that the local (UFS)/work directory is mounted with quotas enabled.

#device          device            mount  FS   fsck mount   mount
#to mount         to fsck           point  type pass at boot options
#
 
/dev/dsk/c0t4d0s0 /dev/rdsk/c0t4d0s0 /work ufs  3    yes     rq

How to Set Up Quotas for a User

1. Become superuser.

2. Use the quota editor to create a temporary file containing one line of quota information for each mounted UFS file system that has a quotas file in its top-level directory.

   # edquota username

   username

   User for whom you want to set up quotas.

3. Change the number of 1-Kbyte disk blocks, both soft and hard, and the number of inodes, both soft and hard, from 0 (the default) to the quotas you specify for each file system.

4. Exit the editor, saving your changes.

5. Verify the user's quota by using the quota command.

   # quota -v username

   -v	Display's user's quota information on all mounted file systems where quotas exist.
   username	Specifies user name to view quota limits.

Examples--Setting Up Quotas for a User

The following example shows the contents of the temporary file opened by edquota on a system where /files is the only mounted file system containing a quotas file in its top-level directory.

fs /files blocks (soft = 0, hard = 0) inodes (soft = 0, hard = 0)

The following example shows the same line in the temporary file after quotas have been set up.

fs /files blocks (soft = 50, hard = 60) inodes (soft = 90, hard = 100)
 

How to Set Up Quotas for Multiple Users

1. Become superuser.

2. Use the quota editor to apply the quotas you already established for a prototype user to the additional users you specify.

   # edquota -p prototype-user username ...

   prototype-user	User name of the account for which you have set up quotas.
   username ..	Specifies one or more user names of additional accounts.

Example--Setting Up Prototype Quotas for Multiple Users

The following example applies the quotas established for user bob to users mary and john.

# edquota -p bob mary john

How to Check Quota Consistency

To ensure accurate disk data, the file systems being checked should be quiescent when you run the quotacheck command manually. The quotacheck command is run automatically when a system is rebooted.

1. Become superuser.

2. Run a consistency check on UFS file systems. See the quotacheck.

   # quotacheck [ -v ] -a | filesystem

   -v	(Optional) Identifies the disk quotas for each user on a particular file system.
   -a	Checks all file systems with an rq entry in the /etc/vfstab file.
   filesystem	Specifies a file system to check.

Example--Checking Quota Consistency

The following example checks quotas for the /export/home file system on the /dev/rdsk/c0t0d0s7 slice. The /export/home file system is the only file system with an rq entry in the /etc/vfstab file.

# quotacheck -va
*** Checking quotas for /dev/rdsk/c0t0d0s7 (/export/home)

How to Turn Quotas On

1. Become superuser.

2. Turn file system quotas on by using the quotaon command.

   # quotaon [-v] -a | ffilesystem ...]

   -v	(Optional) Verbose option.
   -a	Turns quotas on for all file systems with an rq entry in the /etc/vfstab file.
   filesystem ...	Turns quotas on for one or more file systems that you specify.

Example--Turning Quotas On

The following example turns quotas on for the file systems on the /dev/dsk/c0t4d0s2 and /dev/dsk/c0t3d0s2 slices.

# quotaon -v /dev/dsk/c0t4d0s2 /dev/dsk/c0t3d0s2
/dev/dsk/c0t4d0s2: quotas turned on
/dev/dsk/c0t3d0s2: quotas turned on

Checking Quotas

After you have set up and turned on disk and inode quotas, you can check for users who exceed their quotas. In addition, you can check quota information for entire file systems.

Table 58-3 describes the commands you use to check quotas.

How to Check for Exceeded Quotas

You can display the quotas and disk use for individual users on file systems on which quotas have been activated by using the quota command.

1. Become superuser.

2. Display user quotas for mounted file systems where quotas are enabled.

   # quota [-v] username

   -v	(Optional) Displays users' quotas on all mounted file systems that have quotas.
   username	Is the login name or UID of a user's account.

Example--Checking for Exceeded Quotas

The following example shows that the user account identified by UID 301 has a quota of one Kbyte but has not used any disk space.

# quota -v 301
Disk quotas for bob (uid 301):
Filesystem  usage  quota limit timeleft files quota  limit timeleft
/export/home   0      1     2             0      2      3

How to Check Quotas on a File System

Display the quotas and disk use for all users on one or more file systems by using the repquota command.

1. Become superuser.

2. Display all quotas for one or all file systems, even if there is no usage.

   # repquota [-v] -a | filesystem

   -v	(Optional) Reports on quotas for all users-even those who do not consume resources. (Verbose mode).
   -a	Reports on all file systems.
   filesystem	(Reports on the specified file system.

Example--Checking Quotas on a File System

The following example shows output from the repquota command on a system that has quotas enabled on only one file system (/export/home).

# repquota -va
/dev/dsk/c0t3d0s7 (/export/home):
                  Block limits              File limits
User      used   soft   hard  timeleft  used  soft   hard  timeleft
#301  --            0      1   2.0 days         0      2      3  
#341  --    57     50     60   7.0 days  2      90    100  

Changing and Removing Quotas

You can change quotas to adjust the amount of disk space or number of inodes users can consume. You can also remove quotas for individual users or from entire file systems as needed.

Table 58-4 describes the commands you use to change or remove quotas.

How to Change the Soft Time Limit Default

Users can exceed the soft time limits for their quotas for one week, by default. This means that after a week of repeated violations of the soft time limits of either disk space or inode quotas, the system prevents users from using any more inodes or disk blocks.

You can change the length of time that users may exceed their disk space or inode quotas by using the edquota command.

1. Become superuser.

2. Use the quota editor to create a temporary file containing soft time limits.

   # edquota -t

3. Change the time limits from 0 (the default) to the time limits you specify by numbers and the keywords month, week, day, hour, min, or sec.

4. Exit the editor, saving your changes.

   ---

   Note -

   This procedure doesn't affect current quota violators.

   ---

Examples--Changing the Soft Time Limit Default

The following example shows the contents of the temporary file opened by edquota on a system where /export/home is the only mounted file system with quotas. The 0 (default) value means that the default time limit of one week is used.

fs /export/home blocks time limit = 0 (default), files time limit = 0 (default)

The following example shows the same temporary file after the time limit for exceeding the blocks quota has been changed to one week, and the time limit for exceeding the number of files has been changed to ten days.

fs /export/home blocks time limit = 2 weeks, files time limit = 16 days

How to Change Quotas for a User

1. Become superuser.

2. Use the quota editor to open a temporary file containing one line for each mounted file system that has a quotas file in its top-level directory.

   # edquota username

   username

   User name whose quota will be modified.

   ---

   Caution -

   Although you can specify multiple users as arguments to the edquota command, the information displayed does not show which user it belongs to, which could create some confusion.

   ---

3. Enter the number of 1-Kbyte disk blocks, both soft and hard, and the number of inodes, both soft and hard.

4. Exit the editor, saving your changes.

5. Verify that a user's quota has been correctly changed by using the quota command.

   # quota -v username

   -v	Displays user quota information on all mounted file systems with quotas enabled.
   username	User name whose quota you want to check.

Examples--Changing Quotas for a User

The following example shows the contents of the temporary file opened by edquota on a system where /files is the only mounted file system containing a quotas file in its top-level directory.

fs /files blocks (soft = 0, hard = 0) inodes (soft = 0, hard = 0)

The following example shows the same temporary file after quotas have been changed.

fs /files blocks (soft = 0, hard = 500) inodes (soft = 0, hard = 100)

The following example shows how to verify that the hard quotas for user smith have been changed to 500 1-Kbyte blocks, and 100 inodes.

# quota -v smith
Disk quotas for smith (uid 12):
Filesystem  usage  quota  limit  timeleft  files  quota  limit  timeleft
 
  /files     1       0     500              1       0     100

How to Disable Quotas for a User

1. Become superuser.

2. Use the quota editor to create a temporary file containing one line for each mounted file system that has a quotas file in its top-level directory.

   # edquota username

   username

   User name whose quota will be disabled.

   ---

   Caution -

   Although you can specify multiple users as arguments to the edquota command, the information displayed does not show which user it belongs with, which could create some confusion.

   ---

3. Change the number of 1-Kbyte disk blocks, both soft and hard, and the number of inodes, both soft and hard, to 0 (zero).

   ---

   Note -

   Be sure you change the values to zero. Do not delete the line from the text file.

   ---

4. Exit the editor, saving your changes.

5. Verify that you have disabled a user's quota by using the quota command.

   # quota -v username

   -v	Displays user quota information on all mounted file systems with quotas enabled.
   username	User name (UID) whose quota you want to check.

Examples--Disabling Quotas for a User

The following example shows the contents of the temporary file opened by edquota on a system where /files is the only mounted file system containing a quotas file in its top-level directory.

fs /files blocks (soft = 50, hard = 60) inodes (soft = 90, hard = 100)

The following example shows the same temporary file after quotas have been disabled.

fs /files blocks (soft = 0, hard = 0) inodes (soft = 0, hard = 10)
 

How to Turn Quotas Off

1. Become superuser.

2. Turn file system quotas off.

   # quotaoff [ -v ] -a | filesystem ...

   -v	(Optional) Verbose option.
   -a	Turns quotas off for all file systems.
   filesystem1, 2, 3 ...	Turns quotas off for one or more file systems you specify.

Example--Turning Quotas Off

The following example turns the quotas off for the /export/home file system.

# quotaoff -v /export/home
/export/home: quotas turned off