You can use the quota property to set a limit on the amount of disk space a file system can use. In addition, you can use the reservation property to guarantee that a specified amount of disk space is available to a file system. Both properties apply to the file system on which they are set and all descendents of that file system.
That is, if a quota is set on the tank/home file system, the total amount of disk space used by tank/home and all of its descendents cannot exceed the quota. Similarly, if tank/home is given a reservation, tank/home and all of its descendents draw from that reservation. The amount of disk space used by a file system and all of its descendents is reported by the used property.
The refquota and refreservation properties are used to manage file system space without accounting for disk space consumed by descendents, such as snapshots and clones.
In this Oracle Solaris release, you can set a user or a group quota on the amount of disk space consumed by files that are owned by a particular user or group. The user and group quota properties cannot be set on a volume, on a file system before file system version 4, or on a pool before pool version 15.
Consider the following points to determine which quota and reservation features might best help you manage your file systems:
The quota and reservation properties are convenient for managing disk space consumed by file systems and their descendents.
The refquota and refreservation properties are appropriate for managing disk space consumed by file systems.
Setting the refquota or refreservation property higher than the quota or reservation property has no effect. If you set the quota or refquota property, operations that try to exceed either value fail. It is possible to a exceed a quota that is greater than the refquota. For example, if some snapshot blocks are modified, you might actually exceed the quota before you exceed the refquota.
User and group quotas provide a way to more easily manage disk space with many user accounts, such as in a university environment.
A convenient way to set a quota on a large file system for many different users is to set a default user or group quota.
For more information about setting quotas and reservations, see Setting Quotas on ZFS File Systems and Setting Reservations on ZFS File Systems.
Quotas on ZFS file systems can be set and displayed by using the zfs set and zfs get commands. In the following example, a quota of 10 GB is set on tank/home/jeff:
# zfs set quota=10G tank/home/jeff # zfs get quota tank/home/jeff NAME PROPERTY VALUE SOURCE tank/home/jeff quota 10G local
Quotas also affect the output of the zfs list and df commands. For example:
# zfs list -r tank/home NAME USED AVAIL REFER MOUNTPOINT tank/home 1.45M 66.9G 36K /tank/home tank/home/eric 547K 66.9G 547K /tank/home/eric tank/home/jeff 322K 10.0G 291K /tank/home/jeff tank/home/jeff/ws 31K 10.0G 31K /tank/home/jeff/ws tank/home/lori 547K 66.9G 547K /tank/home/lori tank/home/mark 31K 66.9G 31K /tank/home/mark # df -h /tank/home/jeff Filesystem Size Used Avail Use% Mounted on tank/home/jeff 10G 306K 10G 1% /tank/home/jeff
Note that although tank/home has 66.9 GB of disk space available, tank/home/jeff and tank/home/jeff/ws each have only 10 GB of disk space available, due to the quota on tank/home/jeff.
You can set a refquota on a file system that limits the amount of disk space that the file system can consume. This limit does not include disk space that is consumed by descendents. For example, studentA's 10 GB quota is not impacted by space that is consumed by snapshots.
# zfs set refquota=10g students/studentA # zfs list -t all -r students NAME USED AVAIL REFER MOUNTPOINT students 150M 66.8G 32K /students students/studentA 150M 9.85G 150M /students/studentA students/studentA@yesterday 0 - 150M - # zfs snapshot students/studentA@today # zfs list -t all -r students students 150M 66.8G 32K /students students/studentA 150M 9.90G 100M /students/studentA students/studentA@yesterday 50.0M - 150M - students/studentA@today 0 - 100M -
For additional convenience, you can set another quota on a file system to help manage the disk space that is consumed by snapshots. For example:
# zfs set quota=20g students/studentA # zfs list -t all -r students NAME USED AVAIL REFER MOUNTPOINT students 150M 66.8G 32K /students students/studentA 150M 9.90G 100M /students/studentA students/studentA@yesterday 50.0M - 150M - students/studentA@today 0 - 100M -
In this scenario, studentA might reach the refquota (10 GB) hard limit, but studentA can remove files to recover, even if snapshots exist.
In the preceding example, the smaller of the two quotas (10 GB as compared to 20 GB) is displayed in the zfs list output. To view 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
Enforcement of a file system quota might be delayed by several seconds. This delay means that a user might exceed the file system quota before the system notices that the file system is over quota and refuses additional writes with the EDQUOT error message.
file: initialized 52297728 of 83886080 bytes: Disc quota exceeded
If you did not set any quota for your ZFS file system, then if the file system has reached capacity, the following message is displayed:
file: initialized 9830400 of 10485760 bytes: No space left on device
For more information about the replacement of the legacy systems full message from previous Oracle Solaris releases, log in to your MOS account and search for Doc ID 2136469.1.
You can set a user quota or a group quota by using the zfs userquota or zfs groupquota commands, respectively. For example:
# zfs create students/compsci # zfs set userquota@student1=10G students/compsci # zfs create students/labstaff # zfs set groupquota@labstaff=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@labstaff students/labstaff NAME PROPERTY VALUE SOURCE students/labstaff groupquota@labstaff 20G local
You can display general user or group disk space usage by querying the following properties:
# zfs userspace students/compsci TYPE NAME USED QUOTA POSIX User root 350M none POSIX User student1 426M 10G # zfs groupspace students/labstaff TYPE NAME USED QUOTA POSIX Group labstaff 250M 20G POSIX Group root 350M none
To identify individual user or group disk space usage, query the following properties:
# zfs get userused@student1 students/compsci NAME PROPERTY VALUE SOURCE students/compsci userused@student1 550M local # zfs get groupused@labstaff students/labstaff NAME PROPERTY VALUE SOURCE students/labstaff groupused@labstaff 250 local
The user and group quota properties are not displayed by using the zfs get all dataset command, which displays a list of all of the other file system properties.
You can remove a user quota or group quota as follows:
# zfs set userquota@student1=none students/compsci # zfs set groupquota@labstaff=none students/labstaff
User and group quotas on ZFS file systems provide the following features:
A user quota 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 the –R option.
Unprivileged users can only access their own disk space usage. The root user or a user who has been granted the userused or groupused privilege, can access everyone's user or group disk 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 and group quotas might be delayed by several seconds. This delay means that a user might exceed the user quota before the system notices that the user is 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 350M none POSIX User student1 550M 10M # quota student1 Block limit reached on /students/compsci
If you reset the user quota and the quota limit is no longer exceeded, you can 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 350M none POSIX User student1 550M 10G # quota student1 # quota -v student1 Disk quotas for student1 (uid 102): Filesystem usage quota limit timeleft files quota limit timeleft /students/compsci 563287 10485760 10485760 - - - - -
Starting in the Oracle Solaris 11.3 release, you can set a default user quota or a default group quota that is applied automatically for anyone who does not have a specific quota defined. Similar to specific user and group quotas, default user and group quotas are not inheritable to descendent file systems. In addition, if a default user or group quota is set on a top-level file system, space consumed in descendent file systems is not charged to the top-level file system's default quota.
You can set a default user quota on a large shared file system. For example:
# zfs set defaultuserquota=30gb students/labstaff/admindata
Using a default user quota on a large shared file system allows you to restrict growth without specifying individual user quotas. You can also monitor who is using the top-level file system.
# zfs userspace students/labstaff/admindata TYPE NAME USED QUOTA SOURCE POSIX User admin1 2.00G 30G default POSIX User admin2 4.00G 30G default POSIX User root 3K 30G default
In the above example, each user that doesn't have an existing quota is allowed 30 GB of disk space in students/labstaff/admindata. Contrasting this behavior to setting a 30 GB file system quota on students/labstaff/admindata, means that a cumulative quota of 30 GB would apply to all users who didn't have an existing quota.
You can set a default group quota in a similar way. For example, the following syntax sets a 120 GB quota on the students/math file system. You can use the zfs groupspace command to track usage of a top-level file system with a default group quota.
# zfs set defaultgroupquota=120g students/math # zfs groupspace students/math TYPE NAME USED QUOTA SOURCE POSIX Group root 6K 120G default POSIX Group students 40.0G 120G default
A ZFS reservation is an allocation of disk space from the pool that is guaranteed to be available to a dataset. As such, you cannot reserve disk space for a dataset if that space is not currently available in the pool. The total amount of all outstanding, unconsumed reservations cannot exceed the amount of unused disk space in the pool. ZFS reservations can be set and displayed by using the zfs set and zfs get commands. For example:
# zfs set reservation=5G tank/home/bill # zfs get reservation tank/home/bill NAME PROPERTY VALUE SOURCE tank/home/bill reservation 5G local
Reservations can affect the output of the zfs list command. For example:
# zfs list -r tank/home NAME USED AVAIL REFER MOUNTPOINT tank/home 5.00G 61.9G 37K /tank/home tank/home/bill 31K 66.9G 31K /tank/home/bill tank/home/jeff 337K 10.0G 306K /tank/home/jeff tank/home/lori 547K 61.9G 547K /tank/home/lori tank/home/mark 31K 61.9G 31K /tank/home/mark
Note that tank/home is using 5 GB of disk space, although the total amount of space referred to by tank/home and its descendents is much less than 5 GB. The used space reflects the space reserved for tank/home/bill. Reservations are considered in the used disk space calculation of the parent file system and do count against its quota, reservation, or both.
# zfs set quota=5G pool/filesystem # zfs set reservation=10G pool/filesystem/user1 cannot set reservation for 'pool/filesystem/user1': size is greater than available space
A dataset can use more disk space than its reservation, as long as unreserved space is available in the pool, and the dataset's current usage is below its quota. A dataset cannot consume disk space that has been reserved for another dataset.
Reservations are not cumulative. That is, a second invocation of zfs set to set a reservation does not add its reservation to the existing reservation. Rather, the second reservation replaces the first reservation. For example:
# zfs set reservation=10G tank/home/bill # zfs set reservation=5G tank/home/bill # zfs get reservation tank/home/bill NAME PROPERTY VALUE SOURCE tank/home/bill reservation 5G local
You can set a refreservation reservation to guarantee disk space for a dataset that does not include disk space consumed by snapshots and clones. This reservation is accounted for in the parent dataset's space used calculation, and counts against the parent dataset's quotas and reservations. For example:
# zfs set refreservation=10g profs/prof1 # zfs list NAME USED AVAIL REFER MOUNTPOINT profs 10.0G 23.2G 19K /profs profs/prof1 10G 33.2G 18K /profs/prof1
You can also set a reservation on the same dataset to guarantee dataset space and snapshot space. For example:
# zfs set reservation=20g profs/prof1 # zfs list NAME USED AVAIL REFER MOUNTPOINT profs 20.0G 13.2G 19K /profs profs/prof1 10G 33.2G 18K /profs/prof1
Regular reservations are accounted for in the parent's used space calculation.
In the preceding example, the smaller of the two quotas (10 GB as compared to 20 GB) is displayed in the zfs list output. To view the value of both quotas, use the zfs get command. For example:
# zfs get reservation,refreserv profs/prof1 NAME PROPERTY VALUE SOURCE profs/prof1 reservation 20G local profs/prof1 refreservation 10G local
If refreservation is set, a snapshot is only allowed if sufficient unreserved pool space exists outside of this reservation to accommodate the current number of referenced bytes in the dataset.