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46 .Nd native and user-defined properties of ZFS datasets
49 Properties are divided into two types, native properties and user-defined
54 Native properties either export internal statistics or control ZFS behavior.
55 In addition, native properties are either editable or read-only.
56 User properties have no effect on ZFS behavior, but you can use them to annotate
57 datasets in a way that is meaningful in your environment.
58 For more information about user properties, see the
63 Every dataset has a set of properties that export statistics about the dataset
64 as well as control various behaviors.
65 Properties are inherited from the parent unless overridden by the child.
66 Some properties apply only to certain types of datasets
67 .Pq file systems, volumes, or snapshots .
69 The values of numeric properties can be specified using human-readable suffixes
79 The following are all valid
82 .Li 1536M, 1.5g, 1.50GB .
84 The values of non-numeric properties are case sensitive and must be lowercase,
91 The following native properties consist of read-only statistics about the
93 These properties can be neither set, nor inherited.
94 Native properties apply to all dataset types unless otherwise noted.
95 .Bl -tag -width "usedbyrefreservation"
97 The amount of space available to the dataset and all its children, assuming that
98 there is no other activity in the pool.
99 Because space is shared within a pool, availability can be limited by any number
100 of factors, including physical pool size, quotas, reservations, or other
101 datasets within the pool.
103 This property can also be referred to by its shortened column name,
106 For non-snapshots, the compression ratio achieved for the
108 space of this dataset, expressed as a multiplier.
111 property includes descendant datasets, and, for clones, does not include the
112 space shared with the origin snapshot.
118 Compression can be turned on by running:
119 .Nm zfs Cm set Sy compression Ns = Ns Sy on Ar dataset .
123 The transaction group (txg) in which the dataset was created.
124 Bookmarks have the same
126 as the snapshot they are initially tied to.
127 This property is suitable for ordering a list of snapshots,
128 e.g. for incremental send and receive.
130 The time this dataset was created.
132 For snapshots, this property is a comma-separated list of filesystems or volumes
133 which are clones of this snapshot.
136 property is this snapshot.
139 property is not empty, then this snapshot can not be destroyed
146 The roles of origin and clone can be swapped by promoting the clone with the
152 if the snapshot has been marked for deferred destroy by using the
153 .Nm zfs Cm destroy Fl d
155 Otherwise, the property is
157 .It Sy encryptionroot
158 For encrypted datasets, indicates where the dataset is currently inheriting its
160 Loading or unloading a key for the
162 will implicitly load / unload the key for any inheriting datasets (see
165 .Nm zfs Cm unload-key
167 Clones will always share an
168 encryption key with their origin.
174 .It Sy filesystem_count
175 The total number of filesystems and volumes that exist under this location in
177 This value is only available when a
179 has been set somewhere in the tree under which the dataset resides.
181 Indicates if an encryption key is currently loaded into ZFS.
182 The possible values are
190 .Nm zfs Cm unload-key .
192 The 64 bit GUID of this dataset or bookmark which does not change over its
194 When a snapshot is sent to another pool, the received snapshot has the same GUID.
197 is suitable to identify a snapshot across pools.
198 .It Sy logicalreferenced
199 The amount of space that is
201 accessible by this dataset.
205 The logical space ignores the effect of the
209 properties, giving a quantity closer to the amount of data that applications
211 However, it does include space consumed by metadata.
213 This property can also be referred to by its shortened column name,
216 The amount of space that is
218 consumed by this dataset and all its descendents.
222 The logical space ignores the effect of the
226 properties, giving a quantity closer to the amount of data that applications
228 However, it does include space consumed by metadata.
230 This property can also be referred to by its shortened column name,
233 For file systems, indicates whether the file system is currently mounted.
234 This property can be either
239 A unique identifier for this dataset within the pool.
241 .Sy guid , No the Sy objsetid
242 of a dataset is not transferred to other pools when the snapshot is copied
243 with a send/receive operation.
246 can be reused (for a new dataset) after the dataset is deleted.
248 For cloned file systems or volumes, the snapshot from which the clone was
253 .It Sy receive_resume_token
254 For filesystems or volumes which have saved partially-completed state from
255 .Nm zfs Cm receive Fl s ,
256 this opaque token can be provided to
258 to resume and complete the
261 For bookmarks, this is the list of snapshot guids the bookmark contains a redaction
263 For snapshots, this is the list of snapshot guids the snapshot is redacted with
266 The amount of data that is accessible by this dataset, which may or may not be
267 shared with other datasets in the pool.
268 When a snapshot or clone is created, it initially references the same amount of
269 space as the file system or snapshot it was created from, since its contents are
272 This property can also be referred to by its shortened column name,
274 .It Sy refcompressratio
275 The compression ratio achieved for the
277 space of this dataset, expressed as a multiplier.
281 .It Sy snapshot_count
282 The total number of snapshots that exist under this location in the dataset
284 This value is only available when a
286 has been set somewhere in the tree under which the dataset resides.
295 The amount of space consumed by this dataset and all its descendents.
296 This is the value that is checked against this dataset's quota and reservation.
297 The space used does not include this dataset's reservation, but does take into
298 account the reservations of any descendent datasets.
299 The amount of space that a dataset consumes from its parent, as well as the
300 amount of space that is freed if this dataset is recursively destroyed, is the
301 greater of its space used and its reservation.
303 The used space of a snapshot
309 is space that is referenced exclusively by this snapshot.
310 If this snapshot is destroyed, the amount of
313 Space that is shared by multiple snapshots isn't accounted for in this metric.
314 When a snapshot is destroyed, space that was previously shared with this
315 snapshot can become unique to snapshots adjacent to it, thus changing the used
316 space of those snapshots.
317 The used space of the latest snapshot can also be affected by changes in the
321 space of a snapshot is a subset of the
323 space of the snapshot.
325 The amount of space used, available, or referenced does not take into account
327 Pending changes are generally accounted for within a few seconds.
328 Committing a change to a disk using
332 does not necessarily guarantee that the space usage information is updated
337 properties decompose the
339 properties into the various reasons that space is used.
342 .Sy usedbychildren No +
343 .Sy usedbydataset No +
344 .Sy usedbyrefreservation No +
345 .Sy usedbysnapshots .
346 These properties are only available for datasets created on
350 .It Sy usedbychildren
351 The amount of space used by children of this dataset, which would be freed if
352 all the dataset's children were destroyed.
354 The amount of space used by this dataset itself, which would be freed if the
355 dataset were destroyed
356 .Po after first removing any
358 and destroying any necessary snapshots or descendents
360 .It Sy usedbyrefreservation
361 The amount of space used by a
363 set on this dataset, which would be freed if the
366 .It Sy usedbysnapshots
367 The amount of space consumed by snapshots of this dataset.
368 In particular, it is the amount of space that would be freed if all of this
369 dataset's snapshots were destroyed.
370 Note that this is not simply the sum of the snapshots'
372 properties because space can be shared by multiple snapshots.
373 .It Sy userused Ns @ Ns Ar user
374 The amount of space consumed by the specified user in this dataset.
375 Space is charged to the owner of each file, as displayed by
377 The amount of space charged is displayed by
378 .Nm du No and Nm ls Fl s .
381 command for more information.
383 Unprivileged users can access only their own space usage.
384 The root user, or a user who has been granted the
388 can access everyone's usage.
391 .Sy userused Ns @ Ns Ar ...
392 properties are not displayed by
393 .Nm zfs Cm get Sy all .
394 The user's name must be appended after the
396 symbol, using one of the following forms:
397 .Bl -bullet -compact -offset 4n
406 .Pq Qq joe.smith@mydomain
409 .Pq Qq S-1-123-456-789
412 Files created on Linux always have POSIX owners.
413 .It Sy userobjused Ns @ Ns Ar user
416 property is similar to
418 but instead it counts the number of objects consumed by a user.
419 This property counts all objects allocated on behalf of the user,
420 it may differ from the results of system tools such as
424 .Sy xattr Ns = Ns Sy on
425 is set on a file system additional objects will be created per-file to store
427 These additional objects are reflected in the
429 value and are counted against the user's
431 When a file system is configured to use
432 .Sy xattr Ns = Ns Sy sa
433 no additional internal objects are normally required.
435 This property is set to the number of user holds on this snapshot.
436 User holds are set by using the
439 .It Sy groupused Ns @ Ns Ar group
440 The amount of space consumed by the specified group in this dataset.
441 Space is charged to the group of each file, as displayed by
444 .Sy userused Ns @ Ns Ar user
445 property for more information.
447 Unprivileged users can only access their own groups' space usage.
448 The root user, or a user who has been granted the
452 can access all groups' usage.
453 .It Sy groupobjused Ns @ Ns Ar group
454 The number of objects consumed by the specified group in this dataset.
455 Multiple objects may be charged to the group for each file when extended
456 attributes are in use.
458 .Sy userobjused Ns @ Ns Ar user
459 property for more information.
461 Unprivileged users can only access their own groups' space usage.
462 The root user, or a user who has been granted the
466 can access all groups' usage.
467 .It Sy projectused Ns @ Ns Ar project
468 The amount of space consumed by the specified project in this dataset.
469 Project is identified via the project identifier (ID) that is object-based
471 An object can inherit the project ID from its parent object (if the
472 parent has the flag of inherit project ID that can be set and changed via
475 .Nm zfs project Fl s )
477 The privileged user can set and change object's project
483 Space is charged to the project of each file, as displayed by
488 .Sy userused Ns @ Ns Ar user
489 property for more information.
491 The root user, or a user who has been granted the
495 can access all projects' usage.
496 .It Sy projectobjused Ns @ Ns Ar project
501 but instead it counts the number of objects consumed by project.
503 .Sy xattr Ns = Ns Sy on
504 is set on a fileset, ZFS will create additional objects per-file to store
506 These additional objects are reflected in the
508 value and are counted against the project's
509 .Sy projectobjquota .
510 When a filesystem is configured to use
511 .Sy xattr Ns = Ns Sy sa
512 no additional internal objects are required.
514 .Sy userobjused Ns @ Ns Ar user
515 property for more information.
517 The root user, or a user who has been granted the
521 can access all projects' objects usage.
523 For volumes, specifies the block size of the volume.
526 cannot be changed once the volume has been written, so it should be set at
527 volume creation time.
530 for volumes is 8 Kbytes.
531 Any power of 2 from 512 bytes to 128 Kbytes is valid.
533 This property can also be referred to by its shortened column name,
538 by this dataset, that was written since the previous snapshot
539 .Pq i.e. that is not referenced by the previous snapshot .
540 .It Sy written Ns @ Ns Ar snapshot
543 space written to this dataset since the specified snapshot.
544 This is the space that is referenced by this dataset but was not referenced by
545 the specified snapshot.
549 may be specified as a short snapshot name
550 .Pq just the part after the Sy @ ,
551 in which case it will be interpreted as a snapshot in the same filesystem as
555 may be a full snapshot name
556 .Pq Ar filesystem Ns @ Ns Ar snapshot ,
557 which for clones may be a snapshot in the origin's filesystem
558 .Pq or the origin of the origin's filesystem, etc.
561 The following native properties can be used to change the behavior of a ZFS
565 .Sy aclinherit Ns = Ns Sy discard Ns | Ns Sy noallow Ns | Ns
566 .Sy restricted Ns | Ns Sy passthrough Ns | Ns Sy passthrough-x
568 Controls how ACEs are inherited when files and directories are created.
569 .Bl -tag -compact -offset 4n -width "passthrough-x"
571 does not inherit any ACEs.
573 only inherits inheritable ACEs that specify
581 permissions when the ACE is inherited.
583 inherits all inheritable ACEs without any modifications.
588 .Sy owner@ , group@ , No and Sy everyone@
589 ACEs inherit the execute permission only if the file creation mode also requests
593 When the property value is set to
595 files are created with a mode determined by the inheritable ACEs.
596 If no inheritable ACEs exist that affect the mode, then the mode is set in
597 accordance to the requested mode from the application.
601 property does not apply to POSIX ACLs.
603 .Sy aclmode Ns = Ns Sy discard Ns | Ns Sy groupmask Ns | Ns
604 .Sy passthrough Ns | Ns Sy restricted Ns
606 Controls how an ACL is modified during chmod(2) and how inherited ACEs
607 are modified by the file creation mode:
608 .Bl -tag -compact -offset 4n -width "passthrough"
612 except for those representing
613 the mode of the file or directory requested by
616 reduces permissions granted in all
620 such that they are no greater than the group permissions specified by
623 indicates that no changes are made to the ACL other than creating or updating
624 the necessary ACL entries to represent the new mode of the file or directory.
628 operation to return an error when used on any file or directory which has
629 a non-trivial ACL whose entries can not be represented by a mode.
631 is required to change the set user ID, set group ID, or sticky bits on a file
632 or directory, as they do not have equivalent ACL entries.
635 on a file or directory with a non-trivial ACL when
639 you must first remove all ACL entries which do not represent the current mode.
641 .It Sy acltype Ns = Ns Sy off Ns | Ns Sy nfsv4 Ns | Ns Sy posix
642 Controls whether ACLs are enabled and if so what type of ACL to use.
643 When this property is set to a type of ACL not supported by the current
644 platform, the behavior is the same as if it were set to
646 .Bl -tag -compact -offset 4n -width "posixacl"
648 default on Linux, when a file system has the
650 property set to off then ACLs are disabled.
657 indicates that NFSv4-style ZFS ACLs should be used.
658 These ACLs can be managed with the
664 ZFS ACL type is not yet supported on Linux.
666 indicates POSIX ACLs should be used.
667 POSIX ACLs are specific to Linux and are not functional on other platforms.
668 POSIX ACLs are stored as an extended
669 attribute and therefore will not overwrite any existing NFSv4 ACLs which
676 To obtain the best performance when setting
678 users are strongly encouraged to set the
679 .Sy xattr Ns = Ns Sy sa
681 This will result in the POSIX ACL being stored more efficiently on disk.
682 But as a consequence, all new extended attributes will only be
683 accessible from OpenZFS implementations which support the
684 .Sy xattr Ns = Ns Sy sa
688 property for more details.
689 .It Sy atime Ns = Ns Sy on Ns | Ns Sy off
690 Controls whether the access time for files is updated when they are read.
691 Turning this property off avoids producing write traffic when reading files and
692 can result in significant performance gains, though it might confuse mailers
693 and other similar utilities.
698 are equivalent to the
708 .It Sy canmount Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy noauto
709 If this property is set to
711 the file system cannot be mounted, and is ignored by
712 .Nm zfs Cm mount Fl a .
713 Setting this property to
715 is similar to setting the
719 except that the dataset still has a normal
721 property, which can be inherited.
722 Setting this property to
724 allows datasets to be used solely as a mechanism to inherit properties.
725 One example of setting
726 .Sy canmount Ns = Ns Sy off
727 is to have two datasets with the same
729 so that the children of both datasets appear in the same directory, but might
730 have different inherited characteristics.
734 a dataset can only be mounted and unmounted explicitly.
735 The dataset is not mounted automatically when the dataset is created or
736 imported, nor is it mounted by the
737 .Nm zfs Cm mount Fl a
738 command or unmounted by the
739 .Nm zfs Cm unmount Fl a
742 This property is not inherited.
744 .Sy checksum Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy fletcher2 Ns | Ns
745 .Sy fletcher4 Ns | Ns Sy sha256 Ns | Ns Sy noparity Ns | Ns
746 .Sy sha512 Ns | Ns Sy skein Ns | Ns Sy edonr
748 Controls the checksum used to verify data integrity.
751 which automatically selects an appropriate algorithm
754 but this may change in future releases
758 disables integrity checking on user data.
761 not only disables integrity but also disables maintaining parity for user data.
762 This setting is used internally by a dump device residing on a RAID-Z pool and
763 should not be used by any other dataset.
764 Disabling checksums is
766 a recommended practice.
773 checksum algorithms require enabling the appropriate features on the pool.
781 for more information on these algorithms.
783 Changing this property affects only newly-written data.
785 .Sy compression Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy gzip Ns | Ns
786 .Sy gzip- Ns Ar N Ns | Ns Sy lz4 Ns | Ns Sy lzjb Ns | Ns Sy zle Ns | Ns Sy zstd Ns | Ns
787 .Sy zstd- Ns Ar N Ns | Ns Sy zstd-fast Ns | Ns Sy zstd-fast- Ns Ar N
789 Controls the compression algorithm used for this dataset.
791 Setting compression to
793 indicates that the current default compression algorithm should be used.
794 The default balances compression and decompression speed, with compression ratio
795 and is expected to work well on a wide variety of workloads.
796 Unlike all other settings for this property,
798 does not select a fixed compression type.
799 As new compression algorithms are added to ZFS and enabled on a pool, the
800 default compression algorithm may change.
801 The current default compression algorithm is either
810 compression algorithm is a high-performance replacement for the
813 It features significantly faster compression and decompression, as well as a
814 moderately higher compression ratio than
816 but can only be used on pools with the
822 for details on ZFS feature flags and the
828 compression algorithm is optimized for performance while providing decent data
833 compression algorithm uses the same compression as the
838 level by using the value
845 .Pq best compression ratio .
850 .Po which is also the default for
856 compression algorithm provides both high compression ratios and good performance.
859 level by using the value
866 .Pq best compression ratio .
871 Faster speeds at the cost of the compression ratio can be requested by
876 .Sy zstd-fast- Ns Ar N ,
879 is an integer in [1-9,10,20,30,...,100,500,1000] which maps to a negative
882 The lower the level the faster the compression -
883 .Ar 1000 No provides the fastest compression and lowest compression ratio.
890 compression algorithm compresses runs of zeros.
892 This property can also be referred to by its shortened column name
894 Changing this property affects only newly-written data.
896 When any setting except
898 is selected, compression will explicitly check for blocks consisting of only
899 zeroes (the NUL byte).
900 When a zero-filled block is detected, it is stored as
901 a hole and not compressed using the indicated compression algorithm.
903 Any block being compressed must be no larger than 7/8 of its original size
904 after compression, otherwise the compression will not be considered worthwhile
905 and the block saved uncompressed.
906 Note that when the logical block is less than
907 8 times the disk sector size this effectively reduces the necessary compression
908 ratio; for example, 8kB blocks on disks with 4kB disk sectors must compress to 1/2
909 or less of their original size.
911 .Sy context Ns = Ns Sy none Ns | Ns
912 .Ar SELinux-User : Ns Ar SElinux-Role : Ns Ar Selinux-Type : Ns Ar Sensitivity-Level
914 This flag sets the SELinux context for all files in the file system under
915 a mount point for that file system.
918 for more information.
920 .Sy fscontext Ns = Ns Sy none Ns | Ns
921 .Ar SELinux-User : Ns Ar SElinux-Role : Ns Ar Selinux-Type : Ns Ar Sensitivity-Level
923 This flag sets the SELinux context for the file system file system being
927 for more information.
929 .Sy defcontext Ns = Ns Sy none Ns | Ns
930 .Ar SELinux-User : Ns Ar SElinux-Role : Ns Ar Selinux-Type : Ns Ar Sensitivity-Level
932 This flag sets the SELinux default context for unlabeled files.
935 for more information.
937 .Sy rootcontext Ns = Ns Sy none Ns | Ns
938 .Ar SELinux-User : Ns Ar SElinux-Role : Ns Ar Selinux-Type : Ns Ar Sensitivity-Level
940 This flag sets the SELinux context for the root inode of the file system.
943 for more information.
944 .It Sy copies Ns = Ns Sy 1 Ns | Ns Sy 2 Ns | Ns Sy 3
945 Controls the number of copies of data stored for this dataset.
946 These copies are in addition to any redundancy provided by the pool, for
947 example, mirroring or RAID-Z.
948 The copies are stored on different disks, if possible.
949 The space used by multiple copies is charged to the associated file and dataset,
952 property and counting against quotas and reservations.
954 Changing this property only affects newly-written data.
955 Therefore, set this property at file system creation time by using the
956 .Fl o Sy copies Ns = Ns Ar N
959 Remember that ZFS will not import a pool with a missing top-level vdev.
962 create, for example a two-disk striped pool and set
963 .Sy copies Ns = Ns Ar 2
964 on some datasets thinking you have setup redundancy for them.
965 When a disk fails you will not be able to import the pool
966 and will have lost all of your data.
968 Encrypted datasets may not have
969 .Sy copies Ns = Ns Ar 3
970 since the implementation stores some encryption metadata where the third copy
972 .It Sy devices Ns = Ns Sy on Ns | Ns Sy off
973 Controls whether device nodes can be opened on this file system.
980 are equivalent to the
986 .Sy dedup Ns = Ns Sy off Ns | Ns Sy on Ns | Ns Sy verify Ns | Ns
987 .Sy sha256 Ns Oo , Ns Sy verify Oc Ns | Ns Sy sha512 Ns Oo , Ns Sy verify Oc Ns | Ns Sy skein Ns Oo , Ns Sy verify Oc Ns | Ns
988 .Sy edonr , Ns Sy verify
990 Configures deduplication for a dataset.
993 The default deduplication checksum is
995 (this may change in the future).
998 is enabled, the checksum defined here overrides the
1001 Setting the value to
1003 has the same effect as the setting
1004 .Sy sha256 , Ns Sy verify .
1008 ZFS will do a byte-to-byte comparison in case of two blocks having the same
1009 signature to make sure the block contents are identical.
1012 is mandatory for the
1016 Unless necessary, deduplication should
1018 be enabled on a system.
1024 .Sy dnodesize Ns = Ns Sy legacy Ns | Ns Sy auto Ns | Ns Sy 1k Ns | Ns
1025 .Sy 2k Ns | Ns Sy 4k Ns | Ns Sy 8k Ns | Ns Sy 16k
1027 Specifies a compatibility mode or literal value for the size of dnodes in the
1029 The default value is
1031 Setting this property to a value other than
1032 .Sy legacy No requires the Sy large_dnode No pool feature to be enabled.
1038 if the dataset uses the
1039 .Sy xattr Ns = Ns Sy sa
1040 property setting and the workload makes heavy use of extended attributes.
1042 may be applicable to SELinux-enabled systems, Lustre servers, and Samba
1043 servers, for example.
1044 Literal values are supported for cases where the optimal
1045 size is known in advance and for performance testing.
1051 if you need to receive a send stream of this dataset on a pool that doesn't
1054 feature, or if you need to import this pool on a system that doesn't support the
1055 .Sy large_dnode No feature.
1057 This property can also be referred to by its shortened column name,
1060 .Sy encryption Ns = Ns Sy off Ns | Ns Sy on Ns | Ns Sy aes-128-ccm Ns | Ns
1061 .Sy aes-192-ccm Ns | Ns Sy aes-256-ccm Ns | Ns Sy aes-128-gcm Ns | Ns
1062 .Sy aes-192-gcm Ns | Ns Sy aes-256-gcm
1064 Controls the encryption cipher suite (block cipher, key length, and mode) used
1068 feature to be enabled on the pool.
1071 to be set at dataset creation time.
1074 .Sy encryption Ns = Ns Sy on
1075 when creating a dataset indicates that the default encryption suite will be
1076 selected, which is currently
1078 In order to provide consistent data protection, encryption must be specified at
1079 dataset creation time and it cannot be changed afterwards.
1081 For more details and caveats about encryption see the
1084 .Xr zfs-load-key 8 .
1085 .It Sy keyformat Ns = Ns Sy raw Ns | Ns Sy hex Ns | Ns Sy passphrase
1086 Controls what format the user's encryption key will be provided as.
1087 This property is only set when the dataset is encrypted.
1089 Raw keys and hex keys must be 32 bytes long (regardless of the chosen
1090 encryption suite) and must be randomly generated.
1091 A raw key can be generated with the following command:
1092 .Dl # Nm dd Sy if=/dev/urandom bs=32 count=1 Sy of= Ns Pa /path/to/output/key
1094 Passphrases must be between 8 and 512 bytes long and will be processed through
1095 PBKDF2 before being used (see the
1098 Even though the encryption suite cannot be changed after dataset creation,
1099 the keyformat can be with
1100 .Nm zfs Cm change-key .
1102 .Sy keylocation Ns = Ns Sy prompt Ns | Ns Sy file:// Ns Ar /absolute/file/path Ns | Ns Sy https:// Ns Ar address Ns | Ns Sy http:// Ns Ar address
1104 Controls where the user's encryption key will be loaded from by default for
1108 .Nm zfs Cm mount Fl l .
1109 This property is only set for encrypted datasets which are encryption roots.
1110 If unspecified, the default is
1113 Even though the encryption suite cannot be changed after dataset creation, the
1114 keylocation can be with either
1117 .Nm zfs Cm change-key .
1120 is selected ZFS will ask for the key at the command prompt when it is required
1121 to access the encrypted data (see
1124 This setting will also allow the key to be passed in via the standard input stream,
1125 but users should be careful not to place keys which should be kept secret on
1127 If a file URI is selected, the key will be loaded from the
1128 specified absolute file path.
1129 If an HTTPS or HTTP URL is selected, it will be GETted using
1131 libcurl, or nothing, depending on compile-time configuration and run-time availability.
1133 .Sy SSL_CA_CERT_FILE
1134 environment variable can be set to set the location
1135 of the concatenated certificate store.
1137 .Sy SSL_CA_CERT_PATH
1138 environment variable can be set to override the location
1139 of the directory containing the certificate authority bundle.
1141 .Sy SSL_CLIENT_CERT_FILE
1143 .Sy SSL_CLIENT_KEY_FILE
1144 environment variables can be set to configure the path
1145 to the client certificate and its key.
1146 .It Sy pbkdf2iters Ns = Ns Ar iterations
1147 Controls the number of PBKDF2 iterations that a
1149 encryption key should be run through when processing it into an encryption key.
1150 This property is only defined when encryption is enabled and a keyformat of
1153 The goal of PBKDF2 is to significantly increase the
1154 computational difficulty needed to brute force a user's passphrase.
1155 This is accomplished by forcing the attacker to run each passphrase through a
1156 computationally expensive hashing function many times before they arrive at the
1158 A user who actually knows the passphrase will only have to pay this cost once.
1159 As CPUs become better at processing, this number should be
1160 raised to ensure that a brute force attack is still not possible.
1161 The current default is
1165 This property may be changed with
1166 .Nm zfs Cm change-key .
1167 .It Sy exec Ns = Ns Sy on Ns | Ns Sy off
1168 Controls whether processes can be executed from within this file system.
1169 The default value is
1175 are equivalent to the
1180 .It Sy filesystem_limit Ns = Ns Ar count Ns | Ns Sy none
1181 Limits the number of filesystems and volumes that can exist under this point in
1183 The limit is not enforced if the user is allowed to change the limit.
1185 .Sy filesystem_limit
1188 a descendent of a filesystem that already has a
1189 .Sy filesystem_limit
1190 does not override the ancestor's
1191 .Sy filesystem_limit ,
1192 but rather imposes an additional limit.
1193 This feature must be enabled to be used
1195 .Xr zpool-features 7
1197 .It Sy special_small_blocks Ns = Ns Ar size
1198 This value represents the threshold block size for including small file
1199 blocks into the special allocation class.
1200 Blocks smaller than or equal to this
1201 value will be assigned to the special allocation class while greater blocks
1202 will be assigned to the regular class.
1203 Valid values are zero or a power of two from 512B up to 1M.
1204 The default size is 0 which means no small file blocks
1205 will be allocated in the special class.
1207 Before setting this property, a special class vdev must be added to the
1211 for more details on the special allocation class.
1212 .It Sy mountpoint Ns = Ns Pa path Ns | Ns Sy none Ns | Ns Sy legacy
1213 Controls the mount point used for this file system.
1218 for more information on how this property is used.
1222 property is changed for a file system, the file system and any children that
1223 inherit the mount point are unmounted.
1226 then they remain unmounted.
1227 Otherwise, they are automatically remounted in the new location if the property
1232 or if they were mounted before the property was changed.
1233 In addition, any shared file systems are unshared and shared in the new
1235 .It Sy nbmand Ns = Ns Sy on Ns | Ns Sy off
1236 Controls whether the file system should be mounted with
1238 .Pq Non-blocking mandatory locks .
1239 This is used for SMB clients.
1240 Changes to this property only take effect when the file system is umounted and
1242 Support for these locks is scarce and not described by POSIX.
1243 .It Sy overlay Ns = Ns Sy on Ns | Ns Sy off
1244 Allow mounting on a busy directory or a directory which already contains
1245 files or directories.
1246 This is the default mount behavior for Linux and
1249 On these platforms the property is
1254 to disable overlay mounts for consistency with OpenZFS on other platforms.
1255 .It Sy primarycache Ns = Ns Sy all Ns | Ns Sy none Ns | Ns Sy metadata
1256 Controls what is cached in the primary cache
1258 If this property is set to
1260 then both user data and metadata is cached.
1261 If this property is set to
1263 then neither user data nor metadata is cached.
1264 If this property is set to
1266 then only metadata is cached.
1267 The default value is
1269 .It Sy quota Ns = Ns Ar size Ns | Ns Sy none
1270 Limits the amount of space a dataset and its descendents can consume.
1271 This property enforces a hard limit on the amount of space used.
1272 This includes all space consumed by descendents, including file systems and
1274 Setting a quota on a descendent of a dataset that already has a quota does not
1275 override the ancestor's quota, but rather imposes an additional limit.
1277 Quotas cannot be set on volumes, as the
1279 property acts as an implicit quota.
1280 .It Sy snapshot_limit Ns = Ns Ar count Ns | Ns Sy none
1281 Limits the number of snapshots that can be created on a dataset and its
1285 on a descendent of a dataset that already has a
1287 does not override the ancestor's
1288 .Sy snapshot_limit ,
1289 but rather imposes an additional limit.
1290 The limit is not enforced if the user is allowed to change the limit.
1291 For example, this means that recursive snapshots taken from the global zone are
1292 counted against each delegated dataset within a zone.
1293 This feature must be enabled to be used
1295 .Xr zpool-features 7
1297 .It Sy userquota@ Ns Ar user Ns = Ns Ar size Ns | Ns Sy none
1298 Limits the amount of space consumed by the specified user.
1299 User space consumption is identified by the
1300 .Sy userspace@ Ns Ar user
1303 Enforcement of user quotas may be delayed by several seconds.
1304 This delay means that a user might exceed their quota before the system notices
1305 that they are over quota and begins to refuse additional writes with the
1309 .Nm zfs Cm userspace
1310 command for more information.
1312 Unprivileged users can only access their own groups' space usage.
1313 The root user, or a user who has been granted the
1317 can get and set everyone's quota.
1319 This property is not available on volumes, on file systems before version 4, or
1320 on pools before version 15.
1322 .Sy userquota@ Ns Ar ...
1323 properties are not displayed by
1324 .Nm zfs Cm get Sy all .
1325 The user's name must be appended after the
1327 symbol, using one of the following forms:
1328 .Bl -bullet -compact -offset 4n
1337 .Pq Qq joe.smith@mydomain
1340 .Pq Qq S-1-123-456-789
1343 Files created on Linux always have POSIX owners.
1344 .It Sy userobjquota@ Ns Ar user Ns = Ns Ar size Ns | Ns Sy none
1349 but it limits the number of objects a user can create.
1352 for more information about how objects are counted.
1353 .It Sy groupquota@ Ns Ar group Ns = Ns Ar size Ns | Ns Sy none
1354 Limits the amount of space consumed by the specified group.
1355 Group space consumption is identified by the
1356 .Sy groupused@ Ns Ar group
1359 Unprivileged users can access only their own groups' space usage.
1360 The root user, or a user who has been granted the
1364 can get and set all groups' quotas.
1365 .It Sy groupobjquota@ Ns Ar group Ns = Ns Ar size Ns | Ns Sy none
1370 but it limits number of objects a group can consume.
1373 for more information about how objects are counted.
1374 .It Sy projectquota@ Ns Ar project Ns = Ns Ar size Ns | Ns Sy none
1375 Limits the amount of space consumed by the specified project.
1376 Project space consumption is identified by the
1377 .Sy projectused@ Ns Ar project
1381 for more information about how project is identified and set/changed.
1383 The root user, or a user who has been granted the
1387 can access all projects' quota.
1388 .It Sy projectobjquota@ Ns Ar project Ns = Ns Ar size Ns | Ns Sy none
1393 but it limits number of objects a project can consume.
1396 for more information about how objects are counted.
1397 .It Sy readonly Ns = Ns Sy on Ns | Ns Sy off
1398 Controls whether this dataset can be modified.
1399 The default value is
1405 are equivalent to the
1411 This property can also be referred to by its shortened column name,
1413 .It Sy recordsize Ns = Ns Ar size
1414 Specifies a suggested block size for files in the file system.
1415 This property is designed solely for use with database workloads that access
1416 files in fixed-size records.
1417 ZFS automatically tunes block sizes according to internal algorithms optimized
1418 for typical access patterns.
1420 For databases that create very large files but access them in small random
1421 chunks, these algorithms may be suboptimal.
1424 greater than or equal to the record size of the database can result in
1425 significant performance gains.
1426 Use of this property for general purpose file systems is strongly discouraged,
1427 and may adversely affect performance.
1429 The size specified must be a power of two greater than or equal to
1431 and less than or equal to
1435 feature is enabled on the pool, the size may be up to
1438 .Xr zpool-features 7
1439 for details on ZFS feature flags.
1441 Changing the file system's
1443 affects only files created afterward; existing files are unaffected.
1445 This property can also be referred to by its shortened column name,
1447 .It Sy redundant_metadata Ns = Ns Sy all Ns | Ns Sy most
1448 Controls what types of metadata are stored redundantly.
1449 ZFS stores an extra copy of metadata, so that if a single block is corrupted,
1450 the amount of user data lost is limited.
1451 This extra copy is in addition to any redundancy provided at the pool level
1452 .Pq e.g. by mirroring or RAID-Z ,
1453 and is in addition to an extra copy specified by the
1456 .Pq up to a total of 3 copies .
1457 For example if the pool is mirrored,
1458 .Sy copies Ns = Ns 2 ,
1460 .Sy redundant_metadata Ns = Ns Sy most ,
1461 then ZFS stores 6 copies of most metadata, and 4 copies of data and some
1466 ZFS stores an extra copy of all metadata.
1467 If a single on-disk block is corrupt, at worst a single block of user data
1476 ZFS stores an extra copy of most types of metadata.
1477 This can improve performance of random writes, because less metadata must be
1479 In practice, at worst about 100 blocks
1484 of user data can be lost if a single on-disk block is corrupt.
1485 The exact behavior of which metadata blocks are stored redundantly may change in
1488 The default value is
1490 .It Sy refquota Ns = Ns Ar size Ns | Ns Sy none
1491 Limits the amount of space a dataset can consume.
1492 This property enforces a hard limit on the amount of space used.
1493 This hard limit does not include space used by descendents, including file
1494 systems and snapshots.
1495 .It Sy refreservation Ns = Ns Ar size Ns | Ns Sy none Ns | Ns Sy auto
1496 The minimum amount of space guaranteed to a dataset, not including its
1498 When the amount of space used is below this value, the dataset is treated as if
1499 it were taking up the amount of space specified by
1500 .Sy refreservation .
1503 reservation is accounted for in the parent datasets' space used, and counts
1504 against the parent datasets' quotas and reservations.
1508 is set, a snapshot is only allowed if there is enough free pool space outside of
1509 this reservation to accommodate the current number of
1511 bytes in the dataset.
1517 a volume is thick provisioned
1521 .Sy refreservation Ns = Ns Sy auto
1522 is only supported on volumes.
1526 .Sx Native Properties
1527 section for more information about sparse volumes.
1529 This property can also be referred to by its shortened column name,
1531 .It Sy relatime Ns = Ns Sy on Ns | Ns Sy off
1532 Controls the manner in which the access time is updated when
1533 .Sy atime Ns = Ns Sy on
1535 Turning this property on causes the access time to be updated relative
1536 to the modify or change time.
1537 Access time is only updated if the previous
1538 access time was earlier than the current modify or change time or if the
1539 existing access time hasn't been updated within the past 24 hours.
1540 The default value is
1546 are equivalent to the
1551 .It Sy reservation Ns = Ns Ar size Ns | Ns Sy none
1552 The minimum amount of space guaranteed to a dataset and its descendants.
1553 When the amount of space used is below this value, the dataset is treated as if
1554 it were taking up the amount of space specified by its reservation.
1555 Reservations are accounted for in the parent datasets' space used, and count
1556 against the parent datasets' quotas and reservations.
1558 This property can also be referred to by its shortened column name,
1560 .It Sy secondarycache Ns = Ns Sy all Ns | Ns Sy none Ns | Ns Sy metadata
1561 Controls what is cached in the secondary cache
1563 If this property is set to
1565 then both user data and metadata is cached.
1566 If this property is set to
1568 then neither user data nor metadata is cached.
1569 If this property is set to
1571 then only metadata is cached.
1572 The default value is
1574 .It Sy setuid Ns = Ns Sy on Ns | Ns Sy off
1575 Controls whether the setuid bit is respected for the file system.
1576 The default value is
1582 are equivalent to the
1587 .It Sy sharesmb Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Ar opts
1588 Controls whether the file system is shared by using
1589 .Sy Samba USERSHARES
1590 and what options are to be used.
1591 Otherwise, the file system is automatically shared and unshared with the
1596 If the property is set to on, the
1598 command is invoked to create a
1601 Because SMB shares requires a resource name, a unique resource name is
1602 constructed from the dataset name.
1603 The constructed name is a copy of the
1604 dataset name except that the characters in the dataset name, which would be
1605 invalid in the resource name, are replaced with underscore (_) characters.
1606 Linux does not currently support additional options which might be available
1613 the file systems are unshared.
1615 The share is created with the ACL (Access Control List) "Everyone:F" ("F"
1616 stands for "full permissions", i.e. read and write permissions) and no guest
1617 access (which means Samba must be able to authenticate a real user, system
1618 passwd/shadow, LDAP or smbpasswd based) by default.
1619 This means that any additional access control
1620 (disallow specific user specific access etc) must be done on the underlying file system.
1621 .It Sy sharenfs Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Ar opts
1622 Controls whether the file system is shared via NFS, and what options are to be
1624 A file system with a
1630 command and entries in the
1633 Otherwise, the file system is automatically shared and unshared with the
1638 If the property is set to
1640 the dataset is shared using the default options:
1641 .Dl sec=sys,rw,crossmnt,no_subtree_check
1645 for the meaning of the default options.
1648 command is invoked with options equivalent to the contents of this property.
1652 property is changed for a dataset, the dataset and any children inheriting the
1653 property are re-shared with the new options, only if the property was previously
1655 or if they were shared before the property was changed.
1656 If the new property is
1658 the file systems are unshared.
1659 .It Sy logbias Ns = Ns Sy latency Ns | Ns Sy throughput
1660 Provide a hint to ZFS about handling of synchronous requests in this dataset.
1666 ZFS will use pool log devices
1668 to handle the requests at low latency.
1673 ZFS will not use configured pool log devices.
1674 ZFS will instead optimize synchronous operations for global pool throughput and
1675 efficient use of resources.
1676 .It Sy snapdev Ns = Ns Sy hidden Ns | Ns Sy visible
1677 Controls whether the volume snapshot devices under
1678 .Pa /dev/zvol/ Ns Aq Ar pool
1679 are hidden or visible.
1680 The default value is
1682 .It Sy snapdir Ns = Ns Sy hidden Ns | Ns Sy visible
1683 Controls whether the
1685 directory is hidden or visible in the root of the file system as discussed in
1690 The default value is
1692 .It Sy sync Ns = Ns Sy standard Ns | Ns Sy always Ns | Ns Sy disabled
1693 Controls the behavior of synchronous requests
1694 .Pq e.g. fsync, O_DSYNC .
1696 is the POSIX-specified behavior of ensuring all synchronous requests
1697 are written to stable storage and all devices are flushed to ensure
1698 data is not cached by device controllers
1699 .Pq this is the default .
1701 causes every file system transaction to be written and flushed before its
1702 system call returns.
1703 This has a large performance penalty.
1705 disables synchronous requests.
1706 File system transactions are only committed to stable storage periodically.
1707 This option will give the highest performance.
1708 However, it is very dangerous as ZFS would be ignoring the synchronous
1709 transaction demands of applications such as databases or NFS.
1710 Administrators should only use this option when the risks are understood.
1711 .It Sy version Ns = Ns Ar N Ns | Ns Sy current
1712 The on-disk version of this file system, which is independent of the pool
1714 This property can only be set to later supported versions.
1718 .It Sy volsize Ns = Ns Ar size
1719 For volumes, specifies the logical size of the volume.
1720 By default, creating a volume establishes a reservation of equal size.
1721 For storage pools with a version number of 9 or higher, a
1726 are reflected in an equivalent change to the reservation
1727 .Pq or Sy refreservation .
1730 can only be set to a multiple of
1734 The reservation is kept equal to the volume's logical size to prevent unexpected
1735 behavior for consumers.
1736 Without the reservation, the volume could run out of space, resulting in
1737 undefined behavior or data corruption, depending on how the volume is used.
1738 These effects can also occur when the volume size is changed while it is in use
1739 .Pq particularly when shrinking the size .
1740 Extreme care should be used when adjusting the volume size.
1742 Though not recommended, a
1745 .Qq thin provisioned
1747 can be created by specifying the
1750 .Nm zfs Cm create Fl V
1751 command, or by changing the value of the
1756 property on pool version 8 or earlier
1758 after the volume has been created.
1761 is a volume where the value of
1763 is less than the size of the volume plus the space required to store its
1765 Consequently, writes to a sparse volume can fail with
1767 when the pool is low on space.
1768 For a sparse volume, changes to
1770 are not reflected in the
1771 .Sy refreservation .
1772 A volume that is not sparse is said to be
1773 .Qq thick provisioned .
1774 A sparse volume can become thick provisioned by setting
1778 .It Sy volmode Ns = Ns Sy default Ns | Ns Sy full Ns | Ns Sy geom Ns | Ns Sy dev Ns | Ns Sy none
1779 This property specifies how volumes should be exposed to the OS.
1782 exposes volumes as fully fledged block devices, providing maximal
1786 is just an alias for
1788 and is kept for compatibility.
1791 hides its partitions.
1792 Volumes with property set to
1794 are not exposed outside ZFS, but can be snapshotted, cloned, replicated, etc,
1795 that can be suitable for backup purposes.
1798 means that volumes exposition is controlled by system-wide tunable
1805 are encoded as 1, 2 and 3 respectively.
1806 The default value is
1808 .It Sy vscan Ns = Ns Sy on Ns | Ns Sy off
1809 Controls whether regular files should be scanned for viruses when a file is
1811 In addition to enabling this property, the virus scan service must also be
1812 enabled for virus scanning to occur.
1813 The default value is
1815 This property is not used by OpenZFS.
1816 .It Sy xattr Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy sa
1817 Controls whether extended attributes are enabled for this file system.
1818 Two styles of extended attributes are supported: either directory based
1819 or system attribute based.
1821 The default value of
1823 enables directory based extended attributes.
1824 This style of extended attribute imposes no practical limit
1825 on either the size or number of attributes which can be set on a file.
1826 Although under Linux the
1830 system calls limit the maximum size to 64K.
1831 This is the most compatible
1832 style of extended attribute and is supported by all ZFS implementations.
1834 System attribute based xattrs can be enabled by setting the value to
1836 The key advantage of this type of xattr is improved performance.
1837 Storing extended attributes as system attributes
1838 significantly decreases the amount of disk IO required.
1839 Up to 64K of data may be stored per-file in the space reserved for system attributes.
1840 If there is not enough space available for an extended attribute
1841 then it will be automatically written as a directory based xattr.
1842 System attribute based extended attributes are not accessible
1843 on platforms which do not support the
1844 .Sy xattr Ns = Ns Sy sa
1847 .Sy xattr Ns = Ns Sy sa
1852 The use of system attribute based xattrs is strongly encouraged for users of
1853 SELinux or POSIX ACLs.
1854 Both of these features heavily rely on extended
1855 attributes and benefit significantly from the reduced access time.
1861 are equivalent to the
1866 .It Sy jailed Ns = Ns Sy off Ns | Ns Sy on
1867 Controls whether the dataset is managed from a jail.
1870 for more information.
1873 feature and are not relevant on other platforms.
1874 The default value is
1876 .It Sy zoned Ns = Ns Sy on Ns | Ns Sy off
1877 Controls whether the dataset is managed from a non-global zone.
1878 Zones are a Solaris feature and are not relevant on other platforms.
1879 The default value is
1883 The following three properties cannot be changed after the file system is
1884 created, and therefore, should be set when the file system is created.
1885 If the properties are not set with the
1889 commands, these properties are inherited from the parent dataset.
1890 If the parent dataset lacks these properties due to having been created prior to
1891 these features being supported, the new file system will have the default values
1892 for these properties.
1895 .Sy casesensitivity Ns = Ns Sy sensitive Ns | Ns
1896 .Sy insensitive Ns | Ns Sy mixed
1898 Indicates whether the file name matching algorithm used by the file system
1899 should be case-sensitive, case-insensitive, or allow a combination of both
1901 The default value for the
1907 and POSIX file systems have case-sensitive file names.
1913 property indicates that the file system can support requests for both
1914 case-sensitive and case-insensitive matching behavior.
1915 Currently, case-insensitive matching behavior on a file system that supports
1916 mixed behavior is limited to the SMB server product.
1917 For more information about the
1919 value behavior, see the "ZFS Administration Guide".
1921 .Sy normalization Ns = Ns Sy none Ns | Ns Sy formC Ns | Ns
1922 .Sy formD Ns | Ns Sy formKC Ns | Ns Sy formKD
1924 Indicates whether the file system should perform a
1926 normalization of file names whenever two file names are compared, and which
1927 normalization algorithm should be used.
1928 File names are always stored unmodified, names are normalized as part of any
1930 If this property is set to a legal value other than
1934 property was left unspecified, the
1936 property is automatically set to
1938 The default value of the
1942 This property cannot be changed after the file system is created.
1943 .It Sy utf8only Ns = Ns Sy on Ns | Ns Sy off
1944 Indicates whether the file system should reject file names that include
1945 characters that are not present in the
1948 If this property is explicitly set to
1950 the normalization property must either not be explicitly set or be set to
1952 The default value for the
1956 This property cannot be changed after the file system is created.
1960 .Sy casesensitivity ,
1964 properties are also new permissions that can be assigned to non-privileged users
1965 by using the ZFS delegated administration feature.
1967 .Ss Temporary Mount Point Properties
1968 When a file system is mounted, either through
1970 for legacy mounts or the
1972 command for normal file systems, its mount options are set according to its
1974 The correlation between properties and mount options is as follows:
1975 .Bl -tag -compact -offset Ds -width "rootcontext="
1996 .It Sy fscontext Ns =
1998 .It Sy defcontext Ns =
2000 .It Sy rootcontext Ns =
2004 In addition, these options can be set on a per-mount basis using the
2006 option, without affecting the property that is stored on disk.
2007 The values specified on the command line override the values stored in the
2011 option is an alias for
2012 .Sy nodevices , Ns Sy nosetuid .
2013 These properties are reported as
2018 If the properties are changed while the dataset is mounted, the new setting
2019 overrides any temporary settings.
2022 In addition to the standard native properties, ZFS supports arbitrary user
2024 User properties have no effect on ZFS behavior, but applications or
2025 administrators can use them to annotate datasets
2026 .Pq file systems, volumes, and snapshots .
2028 User property names must contain a colon
2030 character to distinguish them from native properties.
2031 They may contain lowercase letters, numbers, and the following punctuation
2040 The expected convention is that the property name is divided into two portions
2042 .Ar module : Ns Ar property ,
2043 but this namespace is not enforced by ZFS.
2044 User property names can be at most 256 characters, and cannot begin with a dash
2047 When making programmatic use of user properties, it is strongly suggested to use
2048 a reversed DNS domain name for the
2050 component of property names to reduce the chance that two
2051 independently-developed packages use the same property name for different
2054 The values of user properties are arbitrary strings, are always inherited, and
2055 are never validated.
2056 All of the commands that operate on properties
2057 .Po Nm zfs Cm list ,
2062 can be used to manipulate both native properties and user properties.
2065 command to clear a user property.
2066 If the property is not defined in any parent dataset, it is removed entirely.
2067 Property values are limited to 8192 bytes.
projects / mirror_zfs.git / blob