System Administration Commands zfs(1M) NAME zfs - configures ZFS file systems SYNOPSIS zfs [-?] zfs create [-p] [-o property=value] ... filesystem zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume zfs destroy [-rRf] filesystem|volume|snapshot zfs snapshot [-r] [-o property=value]... filesystem@snapname|volume@snapname zfs rollback [-rRf] snapshot zfs clone [-p] [-o property=value] ... snapshot filesystem|volume zfs promote clone-filesystem zfs rename filesystem|volume|snapshot filesystem|volume|snapshot zfs rename [-p] filesystem|volume filesystem|volume zfs rename -r snapshot snapshot zfs list [-r|-d depth][-H][-o property[,...]] [-t type[,...]] [-s property] ... [-S property] ... [filesystem|volume|snapshot] ... zfs set property=value filesystem|volume|snapshot ... zfs get [-r|-d depth][-Hp][-o field[,...]] [-s source[,...]] "all" | property[,...] filesystem|volume|snapshot ... zfs inherit [-r] property filesystem|volume|snapshot ... zfs upgrade [-v] zfs upgrade [-r] [-V version] -a | filesystem zfs userspace [-niHp] [-o field[,...]] [-sS field] ... [-t type [,...]] filesystem|snapshot zfs groupspace [-niHp] [-o field[,...]] [-sS field] ... [-t type [,...]] filesystem|snapshot zfs mount zfs mount [-vO] [-o options] -a | filesystem zfs unmount [-f] -a | filesystem|mountpoint zfs share -a | filesystem zfs unshare -a filesystem|mountpoint zfs send [-vR] [-[iI] snapshot] snapshot zfs receive [-vnFu] filesystem|volume|snapshot zfs receive [-vnFu] -d filesystem zfs allow filesystem|volume zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...] filesystem|volume zfs allow [-ld] -e perm|@setname[,...] filesystem|volume zfs allow -c perm|@setname[,...] filesystem|volume zfs allow -s @setname perm|@setname[,...] filesystem|volume zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[,... ]] filesystem|volume zfs unallow [-rld] -e [perm|@setname[,... ]] filesystem|volume zfs unallow [-r] -c [perm|@setname[ ... ]] filesystem|volume zfs unallow [-r] -s @setname [perm|@setname[,... ]] filesystem|volume DESCRIPTION The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(1M). A dataset is identified by a unique path within the ZFS namespace. For example: pool/{filesystem,volume,snapshot} ...where the maximum length of a dataset name is MAXNAMELEN (256 bytes). A dataset can be one of the following: file system A ZFS dataset of type "filesystem" that can be mounted within the standard system namespace and behaves like other file systems. While ZFS file systems are designed to be POSIX compliant, known issues exist that prevent compliance in some cases. Applications that depend on standards conformance might fail due to nonstandard behavior when checking file system free space. volume A logical volume exported as a raw or block device. This type of dataset should only be used under special cir- cumstances. File systems are typically used in most environments. snapshot A read-only version of a file system or volume at a given point in time. It is specified as filesystem@name or volume@name. ZFS File System Hierarchy A ZFS storage pool is a logical collection of devices that provide space for datasets. A storage pool is also the root of the ZFS file system hierarchy. The root of the pool can be accessed as a file system, such as mounting and unmounting, taking snapshots, and setting properties. The physical storage characteristics, however, are managed by the zpool(1M) command. See zpool(1M) for more information on creating and adminis- tering pools. Snapshots A snapshot is a read-only copy of a file system or volume. Snapshots can be created extremely quickly, and initially consume no additional space within the pool. As data within the active dataset changes, the snapshot consumes more data than would otherwise be shared with the active dataset. Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back, but cannot be accessed indepen- dently. File system snapshots can be accessed under the ".zfs/snapshot" directory in the root of the file system. Snapshots are automatically mounted on demand and may be unmounted at regular intervals. The visibility of the ".zfs" directory can be controlled by the "snapdir" property. Clones A clone is a writable volume or file system whose initial contents are the same as another dataset. As with snapshots, creating a clone is nearly instantaneous, and initially con- sumes no additional space. Clones can only be created from a snapshot. When a snapshot is cloned, it creates an implicit dependency between the parent and child. Even though the clone is created somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long as a clone exists. The "origin" pro- perty exposes this dependency, and the destroy command lists any such dependencies, if they exist. The clone parent-child dependency relationship can be reversed by using the "promote" subcommand. This causes the "origin" file system to become a clone of the specified file system, which makes it possible to destroy the file system that the clone was created from. Mount Points Creating a ZFS file system is a simple operation, so the number of file systems per system is likely to be numerous. To cope with this, ZFS automatically manages mounting and unmounting file systems without the need to edit the /etc/vfstab file. All automatically managed file systems are mounted by ZFS at boot time. By default, file systems are mounted under /path, where path is the name of the file system in the ZFS namespace. Direc- tories are created and destroyed as needed. A file system can also have a mount point set in the mountpoint property. This directory is created as needed, and ZFS automatically mounts the file system when the zfs mount -a command is invoked (without editing /etc/vfstab). The mountpoint property can be inherited, so if pool/home has a mount point of /export/stuff, then pool/home/user automatically inherits a mount point of /export/stuff/user. A file system mountpoint property of none prevents the file system from being mounted. If needed, ZFS file systems can also be managed with tradi- tional tools (mount, umount, /etc/vfstab). If a file system's mount point is set to legacy, ZFS makes no attempt to manage the file system, and the administrator is respon- sible for mounting and unmounting the file system. Zones A ZFS file system can be added to a non-global zone by using the zonecfg add fs subcommand. A ZFS file system that is added to a non-global zone must have its mountpoint property set to legacy. The physical properties of an added file system are con- trolled by the global administrator. However, the zone administrator can create, modify, or destroy files within the added file system, depending on how the file system is mounted. A dataset can also be delegated to a non-global zone by using zonecfg add dataset subcommand. You cannot delegate a dataset to one zone and the children of the same dataset to another zone. The zone administrator can change properties of the dataset or any of its children. However, the quota property is controlled by the global administrator. A ZFS volume can be added as a device to a non-global zone by using zonecfg add device subcommand. However, its physi- cal properties can be modified only by the global adminis- trator. For more information about zonecfg syntax, see zonecfg(1M). After a dataset is delegated to a non-global zone, the zoned property is automatically set. A zoned file system cannot be mounted in the global zone, since the zone administrator might have to set the mount point to an unacceptable value. The global administrator can forcibly clear the zoned pro- perty, though this should be done with extreme care. The global administrator should verify that all the mount points are acceptable before clearing the property. Native Properties Properties are divided into two types, native and user- defined (or "user"). Native properties either export inter- nal statistics or control ZFS behavior. In addition, native properties are either editable or read-only. User properties have no effect on ZFS behavior, but you can use them to annotate datasets in a way that is meaningful in your environment. For more information about user properties, see the "User Properties" section, below. Every dataset has a set of properties that export statistics about the dataset as well as control various behaviors. Pro- perties are inherited from the parent unless overridden by the child. Some properties apply only to certain types of datasets (file systems, volumes, or snapshots). The values of numeric properties can be specified using human-readable suffixes (for example, k, KB, M, Gb, and so forth, up to Z for zettabyte). The following are all valid (and equal) specifications: 1536M, 1.5g, 1.50GB The values of non-numeric properties are case sensitive and must be lowercase, except for mountpoint, sharenfs, and sharesmb. The following native properties consist of read-only statis- tics about the dataset. These properties can be neither set, nor inherited. Native properties apply to all dataset types unless otherwise noted. available The amount of space available to the dataset and all its children, assuming that there is no other activity in the pool. Because space is shared within a pool, availa- bility can be limited by any number of factors, includ- ing physical pool size, quotas, reservations, or other datasets within the pool. This property can also be referred to by its shortened column name, avail. compressratio The compression ratio achieved for this dataset, expressed as a multiplier. Compression can be turned on by running: zfs set compression=on dataset. The default value is off. creation The time this dataset was created. mounted For file systems, indicates whether the file system is currently mounted. This property can be either yes or no. origin For cloned file systems or volumes, the snapshot from which the clone was created. The origin cannot be des- troyed (even with the -r or -f options) so long as a clone exists. referenced The amount of data that is accessible by this dataset, which may or may not be shared with other datasets in the pool. When a snapshot or clone is created, it ini- tially references the same amount of space as the file system or snapshot it was created from, since its con- tents are identical. This property can also be referred to by its shortened column name, refer. type The type of dataset: filesystem, volume, or snapshot. used The amount of space consumed by this dataset and all its descendents. This is the value that is checked against this dataset's quota and reservation. The space used does not include this dataset's reservation, but does take into account the reservations of any descendent datasets. The amount of space that a dataset consumes from its parent, as well as the amount of space that are freed if this dataset is recursively destroyed, is the greater of its space used and its reservation. When snapshots (see the "Snapshots" section) are created, their space is initially shared between the snapshot and the file system, and possibly with previous snapshots. As the file system changes, space that was previously shared becomes unique to the snapshot, and counted in the snapshot's space used. Additionally, deleting snapshots can increase the amount of space unique to (and used by) other snapshots. The amount of space used, available, or referenced does not take into account pending changes. Pending changes are generally accounted for within a few seconds. Com- mitting a change to a disk using fsync(3c) or O_SYNC does not necessarily guarantee that the space usage information is updated immediately. usedby* The usedby* properties decompose the used properties into the various reasons that space is used. Specifi- cally, used = usedbychildren + usedbydataset + used- byrefreservation +, usedbysnapshots. These properties are only available for datasets created on zpool "ver- sion 13" pools. usedbychildren The amount of space used by children of this dataset, which would be freed if all the dataset's children were destroyed. usedbydataset The amount of space used by this dataset itself, which would be freed if the dataset were destroyed (after first removing any refreservation and destroying any necessary snapshots or descendents). usedbyrefreservation The amount of space used by a refreservation set on this dataset, which would be freed if the refreservation was removed. usedbysnapshots The amount of space consumed by snapshots of this dataset. In particular, it is the amount of space that would be freed if all of this dataset's snapshots were destroyed. Note that this is not simply the sum of the snapshots' used properties because space can be shared by multiple snapshots userused@user The amount of space consumed by the specified user in this dataset. Space is charged to the owner of each file, as displayed by ls -l. The amount of space charged is displayed by du and ls -s. See the zfs userspace sub- command for more information. Unprivileged users can access only their own space usage. The root user, or a user who has been granted the userused privilege with zfs allow, can access everyone's usage. The userused@... properties are not displayed by zfs get all. The user's name must be appended after the @ sym- bol, using one of the following forms: o posix name (for example, joe) o posix numeric id (for example, 789) o sid name (for example, joe.smith@mydomain) o sid numeric id (for example, S-1-123-456-789) groupused@group The amount of space consumed by the specified group in this dataset. Space is charged to the group of each file, as displayed by ls -l. See the userused@user pro- perty for more information. Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the groupused privilege with zfs allow, can access all groups' usage. volblocksize=blocksize For volumes, specifies the block size of the volume. The blocksize cannot be changed once the volume has been written, so it should be set at volume creation time. The default blocksize for volumes is 8 Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid. This property can also be referred to by its shortened column name, volblock. The following native properties can be used to change the behavior of a ZFS dataset. aclinherit=discard | noallow | restricted | passthrough | passthrough-x Controls how ACL entries are inherited when files and directories are created. A file system with an aclinherit property of discard does not inherit any ACL entries. A file system with an aclinherit property value of noallow only inherits inheritable ACL entries that specify "deny" permissions. The property value res- tricted (the default) removes the write_acl and write_owner permissions when the ACL entry is inherited. A file system with an aclinherit property value of passthrough inherits all inheritable ACL entries without any modifications made to the ACL entries when they are inherited. A file system with an aclinherit property value of passthrough-x has the same meaning as passthrough, except that the owner@, group@, and every- one@ ACEs inherit the execute permission only if the file creation mode also requests the execute bit. When the property value is set to passthrough, files are created with a mode determined by the inheritable ACEs. If no inheritable ACEs exist that affect the mode, then the mode is set in accordance to the requested mode from the application. aclmode=discard | groupmask | passthrough Controls how an ACL is modified during chmod(2). A file system with an aclmode property of discard deletes all ACL entries that do not represent the mode of the file. An aclmode property of groupmask (the default) reduces user or group permissions. The permissions are reduced, such that they are no greater than the group permission bits, unless it is a user entry that has the same UID as the owner of the file or directory. In this case, the ACL permissions are reduced so that they are no greater than owner permission bits. A file system with an aclmode property of passthrough indicates that no changes are made to the ACL other than generating the necessary ACL entries to represent the new mode of the file or directory. atime=on | off Controls whether the access time for files is updated when they are read. Turning this property off avoids producing write traffic when reading files and can result in significant performance gains, though it might confuse mailers and other similar utilities. The default value is on. canmount=on | off | noauto If this property is set to off, the file system cannot be mounted, and is ignored by zfs mount -a. Setting this property to off is similar to setting the mountpoint property to none, except that the dataset still has a normal mountpoint property, which can be inherited. Set- ting this property to off allows datasets to be used solely as a mechanism to inherit properties. One example of setting canmount=off is to have two datasets with the same mountpoint, so that the children of both datasets appear in the same directory, but might have different inherited characteristics. When the noauto option is set, a dataset can only be mounted and unmounted explicitly. The dataset is not mounted automatically when the dataset is created or imported, nor is it mounted by the zfs mount -a command or unmounted by the zfs unmount -a command. This property is not inherited. checksum=on | off | fletcher2,| fletcher4 | sha256 Controls the checksum used to verify data integrity. The default value is on, which automatically selects an appropriate algorithm (currently, fletcher2, but this may change in future releases). The value off disables integrity checking on user data. Disabling checksums is NOT a recommended practice. compression=on | off | lzjb | gzip | gzip-N Controls the compression algorithm used for this dataset. The lzjb compression algorithm is optimized for performance while providing decent data compression. Setting compression to "on" uses the "lzjb" compression algorithm. The "gzip" compression algorithm uses the same compression as the gzip(1) command. You can specify the "gzip" level by using the value "gzip-N" where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, "gzip" is equivalent to "gzip-6" (which is also the default for gzip(1)). This property can also be referred to by its shortened column name "compress". copies=1 | 2 | 3 Controls the number of copies of data stored for this dataset. These copies are in addition to any redundancy provided by the pool, for example, mirroring or raid-z. The copies are stored on different disks, if possible. The space used by multiple copies is charged to the associated file and dataset, changing the used property and counting against quotas and reservations. Changing this property only affects newly-written data. Therefore, set this property at file system creation time by using the -o copies= option. devices=on | off Controls whether device nodes can be opened on this file system. The default value is on. exec=on | off Controls whether processes can be executed from within this file system. The default value is on. mountpoint=path | none | legacy Controls the mount point used for this file system. See the "Mount Points" section for more information on how this property is used. When the mountpoint property is changed for a file sys- tem, the file system and any children that inherit the mount point are unmounted. If the new value is legacy, then they remain unmounted. Otherwise, they are automat- ically remounted in the new location if the property was previously legacy or none, or if they were mounted before the property was changed. In addition, any shared file systems are unshared and shared in the new loca- tion. nbmand=on | off Controls whether the file system should be mounted with nbmand (Non Blocking mandatory locks). This is used for CIFS clients. Changes to this property only take effect when the file system is umounted and remounted. See mount(1M) for more information on nbmand mounts. primarycache=all | none | metadata Controls what is cached in the primary cache (ARC). If this property is set to all, then both user data and metadata is cached. If this property is set to none, then neither user data nor metadata is cached. If this property is set to metadata, then only metadata is cached. The default value is all. quota=size | none Limits the amount of space a dataset and its descendents can consume. This property enforces a hard limit on the amount of space used. This includes all space consumed by descendents, including file systems and snapshots. Setting a quota on a descendent of a dataset that already has a quota does not override the ancestor's quota, but rather imposes an additional limit. Quotas cannot be set on volumes, as the volsize property acts as an implicit quota. userquota@user=size | none Limits the amount of space consumed by the specified user. User space consumption is identified by the userspace@user property. Enforcement of user quotas may be delayed by several seconds. This delay means that a user might exceed their quota before the system notices that they are over quota and begins to refuse additional writes with the EDQUOT error message . See the zfs userspace subcommand for more information. Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the userquota privilege with zfs allow, can get and set everyone's quota. This property is not available on volumes, on file sys- tems before version 4, or on pools before version 15. The userquota@... properties are not displayed by zfs get all. The user's name must be appended after the @ symbol, using one of the following forms: o posix name (for example, joe) o posix numeric id (for example, 789) o sid name (for example, joe.smith@mydomain) o sid numeric id (for example, S-1-123-456-789) groupquota@group=size | none Limits the amount of space consumed by the specified group. Group space consumption is identified by the userquota@user property. Unprivileged users can access only their own groups' space usage. The root user, or a user who has been granted the groupquota privilege with zfs allow, can get and set all groups' quotas. readonly=on | off Controls whether this dataset can be modified. The default value is off. This property can also be referred to by its shortened column name, rdonly. recordsize=size Specifies a suggested block size for files in the file system. This property is designed solely for use with database workloads that access files in fixed-size records. ZFS automatically tunes block sizes according to internal algorithms optimized for typical access pat- terns. For databases that create very large files but access them in small random chunks, these algorithms may be suboptimal. Specifying a recordsize greater than or equal to the record size of the database can result in significant performance gains. Use of this property for general purpose file systems is strongly discouraged, and may adversely affect performance. The size specified must be a power of two greater than or equal to 512 and less than or equal to 128 Kbytes. Changing the file system's recordsize affects only files created afterward; existing files are unaffected. This property can also be referred to by its shortened column name, recsize. refquota=size | none Limits the amount of space a dataset can consume. This property enforces a hard limit on the amount of space used. This hard limit does not include space used by descendents, including file systems and snapshots. refreservation=size | none The minimum amount of space guaranteed to a dataset, not including its descendents. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by refreservation. The refreservation reservation is accounted for in the parent datasets' space used, and counts against the parent datasets' quotas and reserva- tions. If refreservation is set, a snapshot is only allowed if there is enough free pool space outside of this reserva- tion to accommodate the current number of "referenced" bytes in the dataset. This property can also be referred to by its shortened column name, refreserv. reservation=size | none The minimum amount of space guaranteed to a dataset and its descendents. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by its reservation. Reservations are accounted for in the parent datasets' space used, and count against the parent datasets' quo- tas and reservations. This property can also be referred to by its shortened column name, reserv. secondarycache=all | none | metadata Controls what is cached in the secondary cache (L2ARC). If this property is set to all, then both user data and metadata is cached. If this property is set to none, then neither user data nor metadata is cached. If this property is set to metadata, then only metadata is cached. The default value is all. setuid=on | off Controls whether the set-UID bit is respected for the file system. The default value is on. shareiscsi=on | off Like the sharenfs property, shareiscsi indicates whether a ZFS volume is exported as an iSCSI target. The accept- able values for this property are on, off, and type=disk. The default value is off. In the future, other target types might be supported. For example, tape. You might want to set shareiscsi=on for a file system so that all ZFS volumes within the file system are shared by default. However, setting this property on a file system has no direct effect. sharesmb=on | off | opts Controls whether the file system is shared by using the Solaris CIFS service, and what options are to be used. A file system with the sharesmb property set to off is managed through traditional tools such as sharemgr(1M). Otherwise, the file system is automatically shared and unshared with the zfs share and zfs unshare commands. If the property is set to on, the sharemgr(1M) command is invoked with no options. Otherwise, the sharemgr(1M) command is invoked with options equivalent to the con- tents of this property. Because SMB shares requires a resource name, a unique resource name is constructed from the dataset name. The constructed name is a copy of the dataset name except that the characters in the dataset name, which would be illegal in the resource name, are replaced with under- score (_) characters. A pseudo property "name" is also supported that allows you to replace the data set name with a specified name. The specified name is then used to replace the prefix dataset in the case of inheri- tance. For example, if the dataset data/home/john is set to name=john, then data/home/john has a resource name of john. If a child dataset of data/home/john/backups, it has a resource name of john_backups. When SMB shares are created, the SMB share name appears as an entry in the .zfs/shares directory. You can use the ls or chmod command to display the share-level ACLs on the entries in this directory. When the sharesmb property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously set to off, or if they were shared before the property was changed. If the new property is set to off, the file systems are unshared. sharenfs=on | off | opts Controls whether the file system is shared via NFS, and what options are used. A file system with a sharenfs property of off is managed through traditional tools such as share(1M), unshare(1M), and dfstab(4). Other- wise, the file system is automatically shared and unshared with the zfs share and zfs unshare commands. If the property is set to on, the share(1M) command is invoked with no options. Otherwise, the share(1M) com- mand is invoked with options equivalent to the contents of this property. When the sharenfs property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously "off", or if they were shared before the pro- perty was changed. If the new property is off, the file systems are unshared. + mlslabel=