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diff --git a/man/man7/zpool-features.7 b/man/man7/zpool-features.7 new file mode 100644 index 000000000..83ca91175 --- /dev/null +++ b/man/man7/zpool-features.7 @@ -0,0 +1,842 @@ +.\" +.\" Copyright (c) 2012, 2018 by Delphix. All rights reserved. +.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved. +.\" Copyright (c) 2014, Joyent, Inc. All rights reserved. +.\" The contents of this file are subject to the terms of the Common Development +.\" and Distribution License (the "License"). You may not use this file except +.\" in compliance with the License. You can obtain a copy of the license at +.\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. +.\" +.\" See the License for the specific language governing permissions and +.\" limitations under the License. When distributing Covered Code, include this +.\" CDDL HEADER in each file and include the License file at +.\" usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this +.\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your +.\" own identifying information: +.\" Portions Copyright [yyyy] [name of copyright owner] +.\" Copyright (c) 2019, Klara Inc. +.\" Copyright (c) 2019, Allan Jude +.\" Copyright (c) 2021, Colm Buckley <[email protected]> +.\" +.Dd May 31, 2021 +.Dt ZPOOL-FEATURES 7 +.Os +. +.Sh NAME +.Nm zpool-features +.Nd description of ZFS pool features +. +.Sh DESCRIPTION +ZFS pool on-disk format versions are specified via "features" which replace +the old on-disk format numbers (the last supported on-disk format number is 28). +To enable a feature on a pool use the +.Nm zpool Cm upgrade , +or set the +.Sy feature Ns @ Ns Ar feature-name +property to +.Sy enabled . +Please also see the +.Sx Compatibility feature sets +section for information on how sets of features may be enabled together. +.Pp +The pool format does not affect file system version compatibility or the ability +to send file systems between pools. +.Pp +Since most features can be enabled independently of each other, the on-disk +format of the pool is specified by the set of all features marked as +.Sy active +on the pool. +If the pool was created by another software version +this set may include unsupported features. +. +.Ss Identifying features +Every feature has a GUID of the form +.Ar com.example : Ns Ar feature-name . +The reversed DNS name ensures that the feature's GUID is unique across all ZFS +implementations. +When unsupported features are encountered on a pool they will +be identified by their GUIDs. +Refer to the documentation for the ZFS +implementation that created the pool for information about those features. +.Pp +Each supported feature also has a short name. +By convention a feature's short name is the portion of its GUID which follows the +.Sq \&: +(i.e. +.Ar com.example : Ns Ar feature-name +would have the short name +.Ar feature-name ) , +however a feature's short name may differ across ZFS implementations if +following the convention would result in name conflicts. +. +.Ss Feature states +Features can be in one of three states: +.Bl -tag -width "disabled" +.It Sy active +This feature's on-disk format changes are in effect on the pool. +Support for this feature is required to import the pool in read-write mode. +If this feature is not read-only compatible, +support is also required to import the pool in read-only mode +.Pq see Sx Read-only compatibility . +.It Sy enabled +An administrator has marked this feature as enabled on the pool, but the +feature's on-disk format changes have not been made yet. +The pool can still be imported by software that does not support this feature, +but changes may be made to the on-disk format at any time +which will move the feature to the +.Sy active +state. +Some features may support returning to the +.Sy enabled +state after becoming +.Sy active . +See feature-specific documentation for details. +.It Sy disabled +This feature's on-disk format changes have not been made and will not be made +unless an administrator moves the feature to the +.Sy enabled +state. +Features cannot be disabled once they have been enabled. +.El +.Pp +The state of supported features is exposed through pool properties of the form +.Sy feature Ns @ Ns Ar short-name . +. +.Ss Read-only compatibility +Some features may make on-disk format changes that do not interfere with other +software's ability to read from the pool. +These features are referred to as +.Dq read-only compatible . +If all unsupported features on a pool are read-only compatible, +the pool can be imported in read-only mode by setting the +.Sy readonly +property during import (see +.Xr zpool-import 8 +for details on importing pools). +. +.Ss Unsupported features +For each unsupported feature enabled on an imported pool, a pool property +named +.Sy unsupported Ns @ Ns Ar feature-name +will indicate why the import was allowed despite the unsupported feature. +Possible values for this property are: +.Bl -tag -width "readonly" +.It Sy inactive +The feature is in the +.Sy enabled +state and therefore the pool's on-disk +format is still compatible with software that does not support this feature. +.It Sy readonly +The feature is read-only compatible and the pool has been imported in +read-only mode. +.El +. +.Ss Feature dependencies +Some features depend on other features being enabled in order to function. +Enabling a feature will automatically enable any features it depends on. +. +.Ss Compatibility feature sets +It is sometimes necessary for a pool to maintain compatibility with a +specific on-disk format, by enabling and disabling particular features. +The +.Sy compatibility +feature facilitates this by allowing feature sets to be read from text files. +When set to +.Sy off +(the default), compatibility feature sets are disabled +(i.e. all features are enabled); when set to +.Sy legacy , +no features are enabled. +When set to a comma-separated list of filenames +(each filename may either be an absolute path, or relative to +.Pa /etc/zfs/compatibility.d +or +.Pa /usr/share/zfs/compatibility.d ) , +the lists of requested features are read from those files, +separated by whitespace and/or commas. +Only features present in all files are enabled. +.Pp +Simple sanity checks are applied to the files: +they must be between 1B and 16kB in size, and must end with a newline character. +.Pp +The requested features are applied when a pool is created using +.Nm zpool Cm create Fl o Sy compatibility Ns = Ns Ar … +and controls which features are enabled when using +.Nm zpool Cm upgrade . +.Nm zpool Cm status +will not show a warning about disabled features which are not part +of the requested feature set. +.Pp +The special value +.Sy legacy +prevents any features from being enabled, either via +.Nm zpool Cm upgrade +or +.Nm zpool Cm set Sy feature Ns @ Ns Ar feature-name Ns = Ns Sy enabled . +This setting also prevents pools from being upgraded to newer on-disk versions. +This is a safety measure to prevent new features from being +accidentally enabled, breaking compatibility. +.Pp +By convention, compatibility files in +.Pa /usr/share/zfs/compatibility.d +are provided by the distribution, and include feature sets +supported by important versions of popular distributions, and feature +sets commonly supported at the start of each year. +Compatibility files in +.Pa /etc/zfs/compatibility.d , +if present, will take precedence over files with the same name in +.Pa /usr/share/zfs/compatibility.d . +.Pp +If an unrecognized feature is found in these files, an error message will +be shown. +If the unrecognized feature is in a file in +.Pa /etc/zfs/compatibility.d , +this is treated as an error and processing will stop. +If the unrecognized feature is under +.Pa /usr/share/zfs/compatibility.d , +this is treated as a warning and processing will continue. +This difference is to allow distributions to include features +which might not be recognized by the currently-installed binaries. +.Pp +Compatibility files may include comments: +any text from +.Sq # +to the end of the line is ignored. +.Pp +.Sy Example : +.Bd -literal -compact -offset 4n +.No example# Nm cat Pa /usr/share/zfs/compatibility.d/grub2 +# Features which are supported by GRUB2 +async_destroy +bookmarks +embedded_data +empty_bpobj +enabled_txg +extensible_dataset +filesystem_limits +hole_birth +large_blocks +lz4_compress +spacemap_histogram + +.No example# Nm zpool Cm create Fl o Sy compatibility Ns = Ns Ar grub2 Ar bootpool Ar vdev +.Ed +.Pp +See +.Xr zpool-create 8 +and +.Xr zpool-upgrade 8 +for more information on how these commands are affected by feature sets. +. +.de feature +.It Sy \\$2 +.Bl -tag -compact -width "READ-ONLY COMPATIBLE" +.It GUID +.Sy \\$1:\\$2 +.if !"\\$4"" \{\ +.It DEPENDENCIES +\fB\\$4\fP\c +.if !"\\$5"" , \fB\\$5\fP\c +.if !"\\$6"" , \fB\\$6\fP\c +.if !"\\$7"" , \fB\\$7\fP\c +.if !"\\$8"" , \fB\\$8\fP\c +.if !"\\$9"" , \fB\\$9\fP\c +.\} +.It READ-ONLY COMPATIBLE +\\$3 +.El +.Pp +.. +. +.ds instant-never \ +.No This feature becomes Sy active No as soon as it is enabled \ +and will never return to being Sy enabled . +. +.ds remount-upgrade \ +.No Each filesystem will be upgraded automatically when remounted, \ +or when a new file is created under that filesystem. \ +The upgrade can also be triggered on filesystems via \ +Nm zfs Cm set Sy version Ns = Ns Sy current Ar fs . \ +No The upgrade process runs in the background and may take a while to complete \ +for filesystems containing large amounts of files. +. +.de checksum-spiel +When the +.Sy \\$1 +feature is set to +.Sy enabled , +the administrator can turn on the +.Sy \\$1 +checksum on any dataset using +.Nm zfs Cm set Sy checksum Ns = Ns Sy \\$1 Ar dset +.Po see Xr zfs-set 8 Pc . +This feature becomes +.Sy active +once a +.Sy checksum +property has been set to +.Sy \\$1 , +and will return to being +.Sy enabled +once all filesystems that have ever had their checksum set to +.Sy \\$1 +are destroyed. +.. +. +.Sh FEATURES +The following features are supported on this system: +.Bl -tag -width Ds +.feature org.zfsonlinux allocation_classes yes +This feature enables support for separate allocation classes. +.Pp +This feature becomes +.Sy active +when a dedicated allocation class vdev (dedup or special) is created with the +.Nm zpool Cm create No or Nm zpool Cm add No commands . +With device removal, it can be returned to the +.Sy enabled +state if all the dedicated allocation class vdevs are removed. +. +.feature com.delphix async_destroy yes +Destroying a file system requires traversing all of its data in order to +return its used space to the pool. +Without +.Sy async_destroy , +the file system is not fully removed until all space has been reclaimed. +If the destroy operation is interrupted by a reboot or power outage, +the next attempt to open the pool will need to complete the destroy +operation synchronously. +.Pp +When +.Sy async_destroy +is enabled, the file system's data will be reclaimed by a background process, +allowing the destroy operation to complete +without traversing the entire file system. +The background process is able to resume +interrupted destroys after the pool has been opened, eliminating the need +to finish interrupted destroys as part of the open operation. +The amount of space remaining to be reclaimed by the background process +is available through the +.Sy freeing +property. +.Pp +This feature is only +.Sy active +while +.Sy freeing +is non-zero. +. +.feature com.delphix bookmarks yes extensible_dataset +This feature enables use of the +.Nm zfs Cm bookmark +command. +.Pp +This feature is +.Sy active +while any bookmarks exist in the pool. +All bookmarks in the pool can be listed by running +.Nm zfs Cm list Fl t Sy bookmark Fl r Ar poolname . +. +.feature com.datto bookmark_v2 no bookmark extensible_dataset +This feature enables the creation and management of larger bookmarks which are +needed for other features in ZFS. +.Pp +This feature becomes +.Sy active +when a v2 bookmark is created and will be returned to the +.Sy enabled +state when all v2 bookmarks are destroyed. +. +.feature com.delphix bookmark_written no bookmark extensible_dataset bookmark_v2 +This feature enables additional bookmark accounting fields, enabling the +.Sy written Ns # Ns Ar bookmark +property (space written since a bookmark) and estimates of +send stream sizes for incrementals from bookmarks. +.Pp +This feature becomes +.Sy active +when a bookmark is created and will be +returned to the +.Sy enabled +state when all bookmarks with these fields are destroyed. +. +.feature org.openzfs device_rebuild yes +This feature enables the ability for the +.Nm zpool Cm attach +and +.Nm zpool Cm replace +commands to perform sequential reconstruction +(instead of healing reconstruction) when resilvering. +.Pp +Sequential reconstruction resilvers a device in LBA order without immediately +verifying the checksums. +Once complete, a scrub is started, which then verifies the checksums. +This approach allows full redundancy to be restored to the pool +in the minimum amount of time. +This two-phase approach will take longer than a healing resilver +when the time to verify the checksums is included. +However, unless there is additional pool damage, +no checksum errors should be reported by the scrub. +This feature is incompatible with raidz configurations. +. +This feature becomes +.Sy active +while a sequential resilver is in progress, and returns to +.Sy enabled +when the resilver completes. +. +.feature com.delphix device_removal no +This feature enables the +.Nm zpool Cm remove +command to remove top-level vdevs, +evacuating them to reduce the total size of the pool. +.Pp +This feature becomes +.Sy active +when the +.Nm zpool Cm remove +command is used +on a top-level vdev, and will never return to being +.Sy enabled . +. +.feature org.openzfs draid no +This feature enables use of the +.Sy draid +vdev type. +dRAID is a variant of raidz which provides integrated distributed +hot spares that allow faster resilvering while retaining the benefits of raidz. +Data, parity, and spare space are organized in redundancy groups +and distributed evenly over all of the devices. +.Pp +This feature becomes +.Sy active +when creating a pool which uses the +.Sy draid +vdev type, or when adding a new +.Sy draid +vdev to an existing pool. +. +.feature org.illumos edonr no extensible_dataset +This feature enables the use of the Edon-R hash algorithm for checksum, +including for nopwrite (if compression is also enabled, an overwrite of +a block whose checksum matches the data being written will be ignored). +In an abundance of caution, Edon-R requires verification when used with +dedup: +.Nm zfs Cm set Sy dedup Ns = Ns Sy edonr , Ns Sy verify +.Po see Xr zfs-set 8 Pc . +.Pp +Edon-R is a very high-performance hash algorithm that was part +of the NIST SHA-3 competition. +It provides extremely high hash performance (over 350% faster than SHA-256), +but was not selected because of its unsuitability +as a general purpose secure hash algorithm. +This implementation utilizes the new salted checksumming functionality +in ZFS, which means that the checksum is pre-seeded with a secret +256-bit random key (stored on the pool) before being fed the data block +to be checksummed. +Thus the produced checksums are unique to a given pool, +preventing hash collision attacks on systems with dedup. +.Pp +.checksum-spiel edonr +.Pp +.Fx does not support the Sy edonr No feature. +. +.feature com.delphix embedded_data no +This feature improves the performance and compression ratio of +highly-compressible blocks. +Blocks whose contents can compress to 112 bytes +or smaller can take advantage of this feature. +.Pp +When this feature is enabled, the contents of highly-compressible blocks are +stored in the block "pointer" itself (a misnomer in this case, as it contains +the compressed data, rather than a pointer to its location on disk). +Thus the space of the block (one sector, typically 512B or 4kB) is saved, +and no additional I/O is needed to read and write the data block. +. +\*[instant-never] +. +.feature com.delphix empty_bpobj yes +This feature increases the performance of creating and using a large +number of snapshots of a single filesystem or volume, and also reduces +the disk space required. +.Pp +When there are many snapshots, each snapshot uses many Block Pointer +Objects (bpobjs) to track blocks associated with that snapshot. +However, in common use cases, most of these bpobjs are empty. +This feature allows us to create each bpobj on-demand, +thus eliminating the empty bpobjs. +.Pp +This feature is +.Sy active +while there are any filesystems, volumes, +or snapshots which were created after enabling this feature. +. +.feature com.delphix enabled_txg yes +Once this feature is enabled, ZFS records the transaction group number +in which new features are enabled. +This has no user-visible impact, but other features may depend on this feature. +.Pp +This feature becomes +.Sy active + as soon as it is enabled and will +never return to being +.Sy enabled . +. +.feature com.datto encryption no bookmark_v2 extensible_dataset +This feature enables the creation and management of natively encrypted datasets. +.Pp +This feature becomes +.Sy active +when an encrypted dataset is created and will be returned to the +.Sy enabled +state when all datasets that use this feature are destroyed. +. +.feature com.delphix extensible_dataset no +This feature allows more flexible use of internal ZFS data structures, +and exists for other features to depend on. +.Pp +This feature will be +.Sy active +when the first dependent feature uses it, and will be returned to the +.Sy enabled +state when all datasets that use this feature are destroyed. +. +.feature com.joyent filesystem_limits yes extensible_dataset +This feature enables filesystem and snapshot limits. +These limits can be used to control how many filesystems and/or snapshots +can be created at the point in the tree on which the limits are set. +.Pp +This feature is +.Sy active +once either of the limit properties has been set on a dataset. +Once activated the feature is never deactivated. +. +.feature com.delphix hole_birth no enabled_txg +This feature has/had bugs, the result of which is that, if you do a +.Nm zfs Cm send Fl i +.Pq or Fl R , No since it uses Fl i +from an affected dataset, the receiving party will not see any checksum +or other errors, but the resulting destination snapshot +will not match the source. +Its use by +.Nm zfs Cm send Fl i +has been disabled by default +.Pq see Sy send_holes_without_birth_time No in Xr zfs 4 . +.Pp +This feature improves performance of incremental sends +.Pq Nm zfs Cm send Fl i +and receives for objects with many holes. +The most common case of hole-filled objects is zvols. +.Pp +An incremental send stream from snapshot +.Sy A No to snapshot Sy B +contains information about every block that changed between +.Sy A No and Sy B . +Blocks which did not change between those snapshots can be +identified and omitted from the stream using a piece of metadata called +the "block birth time", but birth times are not recorded for holes +(blocks filled only with zeroes). +Since holes created after +.Sy A No cannot be distinguished from holes created before Sy A , +information about every hole in the entire filesystem or zvol +is included in the send stream. +.Pp +For workloads where holes are rare this is not a problem. +However, when incrementally replicating filesystems or zvols with many holes +(for example a zvol formatted with another filesystem) a lot of time will +be spent sending and receiving unnecessary information about holes that +already exist on the receiving side. +.Pp +Once the +.Sy hole_birth +feature has been enabled the block birth times +of all new holes will be recorded. +Incremental sends between snapshots created after this feature is enabled +will use this new metadata to avoid sending information about holes that +already exist on the receiving side. +.Pp +\*[instant-never] +. +.feature org.open-zfs large_blocks no extensible_dataset +This feature allows the record size on a dataset to be set larger than 128kB. +.Pp +This feature becomes +.Sy active +once a dataset contains a file with a block size larger than 128kB, +and will return to being +.Sy enabled +once all filesystems that have ever had their recordsize larger than 128kB +are destroyed. +. +.feature org.zfsonlinux large_dnode no extensible_dataset +This feature allows the size of dnodes in a dataset to be set larger than 512B. +. +This feature becomes +.Sy active +once a dataset contains an object with a dnode larger than 512B, +which occurs as a result of setting the +.Sy dnodesize +dataset property to a value other than +.Sy legacy . +The feature will return to being +.Sy enabled +once all filesystems that have ever contained a dnode larger than 512B +are destroyed. +Large dnodes allow more data to be stored in the bonus buffer, +thus potentially improving performance by avoiding the use of spill blocks. +. +.feature com.delphix livelist yes +This feature allows clones to be deleted faster than the traditional method +when a large number of random/sparse writes have been made to the clone. +All blocks allocated and freed after a clone is created are tracked by the +the clone's livelist which is referenced during the deletion of the clone. +The feature is activated when a clone is created and remains +.Sy active +until all clones have been destroyed. +. +.feature com.delphix log_spacemap yes com.delphix:spacemap_v2 +This feature improves performance for heavily-fragmented pools, +especially when workloads are heavy in random-writes. +It does so by logging all the metaslab changes on a single spacemap every TXG +instead of scattering multiple writes to all the metaslab spacemaps. +.Pp +\*[instant-never] +. +.feature org.illumos lz4_compress no +.Sy lz4 +is a high-performance real-time compression algorithm that +features significantly faster compression and decompression as well as a +higher compression ratio than the older +.Sy lzjb +compression. +Typically, +.Sy lz4 +compression is approximately 50% faster on compressible data and 200% faster +on incompressible data than +.Sy lzjb . +It is also approximately 80% faster on decompression, +while giving approximately a 10% better compression ratio. +.Pp +When the +.Sy lz4_compress +feature is set to +.Sy enabled , +the administrator can turn on +.Sy lz4 +compression on any dataset on the pool using the +.Xr zfs-set 8 +command. +All newly written metadata will be compressed with the +.Sy lz4 +algorithm. +.Pp +\*[instant-never] +. +.feature com.joyent multi_vdev_crash_dump no +This feature allows a dump device to be configured with a pool comprised +of multiple vdevs. +Those vdevs may be arranged in any mirrored or raidz configuration. +.Pp +When the +.Sy multi_vdev_crash_dump +feature is set to +.Sy enabled , +the administrator can use +.Xr dumpadm 1M +to configure a dump device on a pool comprised of multiple vdevs. +.Pp +Under +.Fx +and Linux this feature is unused, but registered for compatibility. +New pools created on these systems will have the feature +.Sy enabled +but will never transition to +.Sy active , +as this functionality is not required for crash dump support. +Existing pools where this feature is +.Sy active +can be imported. +. +.feature com.delphix obsolete_counts yes device_removal +This feature is an enhancement of +.Sy device_removal , +which will over time reduce the memory used to track removed devices. +When indirect blocks are freed or remapped, +we note that their part of the indirect mapping is "obsolete" – no longer needed. +.Pp +This feature becomes +.Sy active +when the +.Nm zpool Cm remove +command is used on a top-level vdev, and will never return to being +.Sy enabled . +. +.feature org.zfsonlinux project_quota yes extensible_dataset +This feature allows administrators to account the spaces and objects usage +information against the project identifier (ID). +.Pp +The project ID is an object-based attribute. +When upgrading an existing filesystem, +objects without a project ID will be assigned a zero project ID. +When this feature is enabled, newly created objects inherit +their parent directories' project ID if the parent's inherit flag is set +.Pq via Nm chattr Sy [+-]P No or Nm zfs Cm project Fl s Ns | Ns Fl C . +Otherwise, the new object's project ID will be zero. +An object's project ID can be changed at any time by the owner +(or privileged user) via +.Nm chattr Fl p Ar prjid +or +.Nm zfs Cm project Fl p Ar prjid . +.Pp +This feature will become +.Sy active +as soon as it is enabled and will never return to being +.Sy disabled . +\*[remount-upgrade] +. +.feature com.delphix redaction_bookmarks no bookmarks extensible_dataset +This feature enables the use of redacted +.Nm zfs Cm send Ns s , +which create redaction bookmarks storing the list of blocks +redacted by the send that created them. +For more information about redacted sends, see +.Xr zfs-send 8 . +. +.feature com.delphix redacted_datasets no extensible_dataset +This feature enables the receiving of redacted +.Nm zfs Cm send Ns +streams. which create redacted datasets when received. +These datasets are missing some of their blocks, +and so cannot be safely mounted, and their contents cannot be safely read. +For more information about redacted receives, see +.Xr zfs-send 8 . +. +.feature com.datto resilver_defer yes +This feature allows ZFS to postpone new resilvers if an existing one is already +in progress. +Without this feature, any new resilvers will cause the currently +running one to be immediately restarted from the beginning. +.Pp +This feature becomes +.Sy active +once a resilver has been deferred, and returns to being +.Sy enabled +when the deferred resilver begins. +. +.feature org.illumos sha512 no extensible_dataset +This feature enables the use of the SHA-512/256 truncated hash algorithm +(FIPS 180-4) for checksum and dedup. +The native 64-bit arithmetic of SHA-512 provides an approximate 50% +performance boost over SHA-256 on 64-bit hardware +and is thus a good minimum-change replacement candidate +for systems where hash performance is important, +but these systems cannot for whatever reason utilize the faster +.Sy skein No and Sy edonr +algorithms. +.Pp +.checksum-spiel sha512 +. +.feature org.illumos skein no extensible_dataset +This feature enables the use of the Skein hash algorithm for checksum and dedup. +Skein is a high-performance secure hash algorithm that was a +finalist in the NIST SHA-3 competition. +It provides a very high security margin and high performance on 64-bit hardware +(80% faster than SHA-256). +This implementation also utilizes the new salted checksumming +functionality in ZFS, which means that the checksum is pre-seeded with a +secret 256-bit random key (stored on the pool) before being fed the data +block to be checksummed. +Thus the produced checksums are unique to a given pool, +preventing hash collision attacks on systems with dedup. +.Pp +.checksum-spiel skein +. +.feature com.delphix spacemap_histogram yes +This features allows ZFS to maintain more information about how free space +is organized within the pool. +If this feature is +.Sy enabled , +it will be activated when a new space map object is created, or +an existing space map is upgraded to the new format, +and never returns back to being +.Sy enabled . +. +.feature com.delphix spacemap_v2 yes +This feature enables the use of the new space map encoding which +consists of two words (instead of one) whenever it is advantageous. +The new encoding allows space maps to represent large regions of +space more efficiently on-disk while also increasing their maximum +addressable offset. +.Pp +This feature becomes +.Sy active +once it is +.Sy enabled , +and never returns back to being +.Sy enabled . +. +.feature org.zfsonlinux userobj_accounting yes extensible_dataset +This feature allows administrators to account the object usage information +by user and group. +.Pp +\*[instant-never] +\*[remount-upgrade] +. +.feature com.delphix zpool_checkpoint yes +This feature enables the +.Nm zpool Cm checkpoint +command that can checkpoint the state of the pool +at the time it was issued and later rewind back to it or discard it. +.Pp +This feature becomes +.Sy active +when the +.Nm zpool Cm checkpoint +command is used to checkpoint the pool. +The feature will only return back to being +.Sy enabled +when the pool is rewound or the checkpoint has been discarded. +. +.feature org.freebsd zstd_compress no extensible_dataset +.Sy zstd +is a high-performance compression algorithm that features a +combination of high compression ratios and high speed. +Compared to +.Sy gzip , +.Sy zstd +offers slightly better compression at much higher speeds. +Compared to +.Sy lz4 , +.Sy zstd +offers much better compression while being only modestly slower. +Typically, +.Sy zstd +compression speed ranges from 250 to 500 MB/s per thread +and decompression speed is over 1 GB/s per thread. +.Pp +When the +.Sy zstd +feature is set to +.Sy enabled , +the administrator can turn on +.Sy zstd +compression of any dataset using +.Nm zfs Cm set Sy compress Ns = Ns Sy zstd Ar dset +.Po see Xr zfs-set 8 Pc . +This feature becomes +.Sy active +once a +.Sy compress +property has been set to +.Sy zstd , +and will return to being +.Sy enabled +once all filesystems that have ever had their +.Sy compress +property set to +.Sy zstd +are destroyed. +.El +. +.Sh SEE ALSO +.Xr zpool 8 |