Setting Quotas on ZFS File Systems (Solaris ZFS Administration Guide)

Solaris ZFS Administration Guide

Setting Quotas on ZFS File Systems

ZFS quotas can be set and displayed by using the zfs set and zfs get commands. In the following example, a quota of 10 Gbytes is set on tank/home/bonwick.

# zfs set quota=10G tank/home/bonwick
# zfs get quota tank/home/bonwick
NAME              PROPERTY      VALUE                      SOURCE
tank/home/bonwick quota         10.0G                      local

ZFS quotas also impact the output of the zfs list and df commands. For example:

# zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
tank/home             16.5K  33.5G  8.50K  /export/home
tank/home/bonwick     15.0K  10.0G  8.50K  /export/home/bonwick
tank/home/bonwick/ws  6.50K  10.0G  8.50K  /export/home/bonwick/ws
# df -h /export/home/bonwick
Filesystem             size   used  avail capacity  Mounted on
tank/home/bonwick       10G     8K    10G     1%    /export/home/bonwick

Note that although tank/home has 33.5 Gbytes of space available, tank/home/bonwick and tank/home/bonwick/ws only have 10 Gbytes of space available, due to the quota on tank/home/bonwick.

You cannot set a quota to an amount less than is currently being used by a dataset. For example:

# zfs set quota=10K tank/home/bonwick
cannot set quota for 'tank/home/bonwick': size is less than current used or 
reserved space

You can set a refquota on a dataset that limits the amount of space that the dataset can consume. This hard limit does not include space that is consumed by descendents. For example:

# zfs set refquota=10g students/studentA
# zfs list
NAME                USED  AVAIL  REFER  MOUNTPOINT
profs               106K  33.2G    18K  /profs
students           57.7M  33.2G    19K  /students
students/studentA  57.5M  9.94G  57.5M  /students/studentA
# zfs snapshot students/studentA@today
# zfs list
NAME                      USED  AVAIL  REFER  MOUNTPOINT
profs                     106K  33.2G    18K  /profs
students                 57.7M  33.2G    19K  /students
students/studentA        57.5M  9.94G  57.5M  /students/studentA
students/studentA@today      0      -  57.5M  -

For additional convenience, you can set another quota on a dataset to help manage the space that is consumed by snapshots. For example:

# zfs set quota=20g students/studentA
# zfs list
NAME                      USED  AVAIL  REFER  MOUNTPOINT
profs                     106K  33.2G    18K  /profs
students                 57.7M  33.2G    19K  /students
students/studentA        57.5M  9.94G  57.5M  /students/studentA
students/studentA@today      0      -  57.5M  -

In this scenario, studentA might reach the refquota (10 Gbytes) hard limit, but can remove files to recover, even if snapshots exist.

In the above example, the smaller of the two quotas (10 Gbytes versus 20 Gbytes) is displayed in the zfs list output. To see the value of both quotas, use the zfs get command. For example:

# zfs get refquota,quota students/studentA
NAME               PROPERTY  VALUE              SOURCE
students/studentA  refquota  10G                local
students/studentA  quota     20G                local

Setting User or Group Quotas on a ZFS File System

You can set a user or a group quota by using the zfs userquota and zfs groupquota commands as follows:

# zfs create students/compsci
# zfs set userquota@student1=10G students/compsci
# zfs create students/labstaff
# zfs set groupquota@staff=20GB students/labstaff

Display the current user quota or group quota as follows:

# zfs get userquota@student1 students/compsci
NAME              PROPERTY            VALUE               SOURCE
students/compsci  userquota@student1  10G                 local
# zfs get groupquota@staff students/labstaff
NAME               PROPERTY          VALUE             SOURCE
students/labstaff  groupquota@staff  20G               local

You can display general user and group space usage by querying the following properties:

# zfs userspace students/compsci
TYPE        NAME      USED  QUOTA  
POSIX User  root      227M   none  
POSIX User  student1  455M    10G  
# zfs groupspace students/labstaff
TYPE         NAME   USED  QUOTA  
POSIX Group  root   217M   none  
POSIX Group  staff  217M    20G

If you want to identify individual user or group space usage, query the following properties:

# zfs get userused@student1 students/compsci
NAME              PROPERTY           VALUE              SOURCE
students/compsci  userused@student1  455M               local
# zfs get groupused@staff students/labstaff
NAME               PROPERTY         VALUE            SOURCE
students/labstaff  groupused@staff  217M             local

The user and group quota properties are not displayed by using the zfs get all dataset command that displays a listing of all file system properties.

You can remove a user or group quota as follows:

# zfs set userquota@user1=none students/compsci
# zfs set groupquota@staff=none students/labstaff

ZFS user and group quotas provide the following features:

When set on a file system, a user or group quota that is set on a parent file system is not automatically inherited by a descendent file system.
However, the user or group quota is applied when a clone or a snapshot is created from a file system that has a user or group quota. Likewise, a user or group quota is included with the file system when a stream is created by using the zfs send command, even without -R option.
Unprivileged users can only access their own space usage. The root user or a user who has been granted the userused or groupused privilege, can access everyone's user or group space accounting information.
The userquota and groupquota properties cannot be set on ZFS volumes, on a file system prior to file system version 4, or on a pool prior to pool version 15.

Enforcement of user or group quotas might be delayed by several seconds. This delay means that users might exceed their quota before the system notices that they are over quota and refuses additional writes with the EDQUOT error message.

You can use the legacy quota command to review user quotas in an NFS environment, for example, where a ZFS file system is mounted. Without any options, the quota command only displays output if the user's quota is exceeded. For example:

# zfs set userquota@student1=10m students/compsci   
# zfs userspace students/compsci
TYPE        NAME      USED  QUOTA  
POSIX User  root      227M   none  
POSIX User  student1  455M    10M  
# quota student1
Block limit reached on /students/compsci

If you reset the quota and the quota limit is no longer exceeded, you will need to use the quota -v command to review the user's quota. For example:

# zfs set userquota@student1=10GB students/compsci 
# zfs userspace students/compsci
TYPE        NAME      USED  QUOTA  
POSIX User  root      227M   none  
POSIX User  student1  455M    10G  
# quota student1
# quota -v student1
Disk quotas for student1 (uid 201):
Filesystem     usage  quota  limit    timeleft  files  quota  limit    timeleft
/students/compsci
              466029 10485760 10485760