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ZPOOL-FEATURES(5)	      File Formats Manual	     ZPOOL-FEATURES(5)

NAME
       zpool-features -	ZFS pool feature descriptions

DESCRIPTION
       ZFS pool	on-disk	format versions	are specified via "features" which re-
       place the old on-disk format numbers (the last supported	on-disk	format
       number is 28). To enable	a feature on a pool use	the upgrade subcommand
       of the zpool(8) command,	or set the  feature@feature_name  property  to
       enabled.

       The  pool  format  does not affect file system version compatibility or
       the ability to send file	systems	between	pools.

       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 active	on the pool. If	the pool was created by	another	 soft-
       ware version this set may include unsupported features.

   Identifying features
       Every  feature has a GUID of the	form com.example:feature_name. The re-
       versed 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.

       Each supported feature also has a short name. By	convention a feature's
       short  name  is	the  portion  of  its GUID which follows the ':' (e.g.
       com.example:feature_name	would have the short name feature_name),  how-
       ever  a	feature's  short name may differ across	ZFS implementations if
       following the convention	would result in	name conflicts.

   Feature states
       Features	can be in one of three states:

       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 (see "Read-only compatibility").

       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  fea-
		   ture	to the active state. Some features may support return-
		   ing to the enabled state after becoming  active.  See  fea-
		   ture-specific documentation for details.

       disabled
		   This	 feature's  on-disk  format changes have not been made
		   and will not	be made	unless an administrator	moves the fea-
		   ture	to the enabled state. Features cannot be disabled once
		   they	have been enabled.

       The state of supported features is exposed through pool	properties  of
       the form	feature@short_name.

   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 "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 readonly property during import (see zpool(8) for
       details on importing pools).

   Unsupported features
       For each	unsupported feature enabled on an imported pool	a  pool	 prop-
       erty  named  unsupported@feature_name  will indicate why	the import was
       allowed despite the unsupported feature.	Possible values	for this prop-
       erty are:

       inactive
		   The	feature	 is  in	 the  enabled  state and therefore the
		   pool's on-disk format is  still  compatible	with  software
		   that	does not support this feature.

       readonly
		   The	feature	 is read-only compatible and the pool has been
		   imported in read-only mode.

   Feature dependencies
       Some features depend on other features being enabled in order to	 func-
       tion  properly.	Enabling  a feature will automatically enable any fea-
       tures it	depends	on.

FEATURES
       The following features are supported on this system:

       allocation_classes

	   GUID			  org.zfsonlinux:allocation_classes
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   This	feature	enables	support	for separate allocation	classes.

	   This	feature	becomes	active when a dedicated	allocation class  vdev
	   (dedup  or  special)	 is created with the zpool create or zpool add
	   subcommands.	With device removal, it	can be returned	to the enabled
	   state if all	the dedicated allocation class vdevs are removed.

       async_destroy

	   GUID			  com.delphix:async_destroy
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   Destroying a	file system requires traversing	all of its data	in or-
	   der to return its used space	to the pool. Without async_destroy the
	   file	 system	 is  not  fully	 removed  until	all space has been re-
	   claimed. If the destroy operation is	interrupted  by	 a  reboot  or
	   power  outage  the  next attempt to open the	pool will need to com-
	   plete the destroy operation synchronously.

	   When	async_destroy is enabled the file system's data	 will  be  re-
	   claimed  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 re-
	   claimed by the background process is	available through the  freeing
	   property.

	   This	feature	is only	active while freeing is	non-zero.

       bookmarks

	   GUID			  com.delphix:bookmarks
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  extensible_dataset

	   This	feature	enables	use of the zfs bookmark	subcommand.

	   This	 feature is active while any bookmarks exist in	the pool.  All
	   bookmarks in	the pool can be	listed by running zfs list -t bookmark
	   -r poolname.

       bookmark_v2

	   GUID			  com.datto:bookmark_v2
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  bookmark, extensible_dataset

	   This	 feature  enables  the creation	and management of larger book-
	   marks which are needed for other features in	ZFS.

	   This	feature	becomes	active when a v2 bookmark is created and  will
	   be  returned	 to  the  enabled  state when all v2 bookmarks are de-
	   stroyed.

       bookmark_written

	   GUID			  com.delphix:bookmark_written
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  bookmark, extensible_dataset,	bookmark_v2

	   This	feature	enables	additional  bookmark  accounting  fields,  en-
	   abling the written#<bookmark> property (space written since a book-
	   mark) and estimates of send	stream	sizes  for  incrementals  from
	   bookmarks.

	   This	 feature becomes active	when a bookmark	is created and will be
	   returned to the enabled state when all bookmarks with these	fields
	   are destroyed.

       device_rebuild

	   GUID			  org.openzfs:device_rebuild
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   This	feature	enables	the ability for	the zpool attach and zpool re-
	   place subcommands to	perform	sequential reconstruction (instead  of
	   healing reconstruction) when	resilvering.

	   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 re-
	   silver 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  active  while  a  sequential	resilver is in
	   progress, and returns to enabled when the resilver completes.

       device_removal

	   GUID			  com.delphix:device_removal
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  none

	   This	feature	enables	the zpool remove  subcommand  to  remove  top-
	   level vdevs,	evacuating them	to reduce the total size of the	pool.

	   This	 feature  becomes  active  when	the zpool remove subcommand is
	   used	on a top-level vdev, and will never return to being enabled.

       edonr

	   GUID			  org.illumos:edonr
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  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 writ-
	   ten	will be	ignored).  In an abundance of caution, Edon-R requires
	   verification	when used with dedup: zfs set dedup=edonr,verify.  See
	   zfs(8).

	   Edon-R  is  a very high-performance hash algorithm that was part of
	   the NIST SHA-3 competition. It provides extremely high hash perfor-
	   mance (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 function-
	   ality 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.

	   When	 the  edonr  feature  is set to	enabled, the administrator can
	   turn	on the edonr checksum on any dataset using the zfs set	check-
	   sum=edonr.  See zfs(8). This	feature	becomes	active once a checksum
	   property has	been set to edonr, and will return  to	being  enabled
	   once	all filesystems	that have ever had their checksum set to edonr
	   are destroyed.

	   FreeBSD does	not support the	edonr feature.

       embedded_data

	   GUID			  com.delphix:embedded_data
	   READ-ONLY COMPATIBLE	  no

	   DEPENDENCIES		  none

	   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.

	   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 512 bytes or 4KB) is saved,  and  no  additional  i/o  is
	   needed to read and write the	data block.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled.

       empty_bpobj

	   GUID			  com.delphix:empty_bpobj
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   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.

	   When	there are  many	 snapshots,  each  snapshot  uses  many	 Block
	   Pointer  Objects  (bpobj's)	to  track  blocks associated with that
	   snapshot.  However, in common use cases, most of these bpobj's  are
	   empty.  This	feature	allows us to create each bpobj on-demand, thus
	   eliminating the empty bpobjs.

	   This	feature	is active while	there are any filesystems, volumes, or
	   snapshots which were	created	after enabling this feature.

       enabled_txg

	   GUID			  com.delphix:enabled_txg
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   Once	this feature is	enabled	ZFS records the	transaction group num-
	   ber in which	new features are enabled. This has no user-visible im-
	   pact, but other features may	depend on this feature.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled.

       encryption

	   GUID			  com.datto:encryption
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  bookmark_v2, extensible_dataset

	   This	feature	enables	the creation and management  of	 natively  en-
	   crypted datasets.

	   This	 feature  becomes  active when an encrypted dataset is created
	   and will be returned	to the enabled state when  all	datasets  that
	   use this feature are	destroyed.

       extensible_dataset

	   GUID			  com.delphix:extensible_dataset
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  none

	   This	 feature  allows more flexible use of internal ZFS data	struc-
	   tures, and exists for other features	to depend on.

	   This	feature	will be	active when the	first dependent	 feature  uses
	   it,	and  will  be  returned	to the enabled state when all datasets
	   that	use this feature are destroyed.

       filesystem_limits

	   GUID			  com.joyent:filesystem_limits
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  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.

	   This	feature	is active once either of the limit properties has been
	   set on a dataset. Once activated the	feature	is never deactivated.

       hole_birth

	   GUID			  com.delphix:hole_birth
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  enabled_txg

	   This	feature	has/had	bugs, the result of which is that, if you do a
	   zfs send -i (or -R, since it	uses -i) from an affected dataset, the
	   receiver will not see any checksum or other errors, but the result-
	   ing destination snapshot will not match the source.	Its use	by zfs
	   send	 -i  has  been	disabled by default.  See the send_holes_with-
	   out_birth_time module parameter in zfs-module-parameters(5).

	   This	feature	improves performance of	incremental  sends  (zfs  send
	   -i)	and receives for objects with many holes. The most common case
	   of hole-filled objects is zvols.

	   An incremental send stream from snapshot A to snapshot  B  contains
	   information	about every block that changed between A and 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 A cannot be
	   distinguished from holes created before A, information about	 every
	   hole	 in  the  entire  filesystem  or  zvol is included in the send
	   stream.

	   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.

	   Once	the hole_birth feature has been	enabled	the block birth	 times
	   of  all new holes will be recorded. Incremental sends between snap-
	   shots created after this feature is enabled will use	this new meta-
	   data	to avoid sending information about holes that already exist on
	   the receiving side.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled.

       large_blocks

	   GUID			  org.open-zfs:large_blocks
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   The	large_block  feature allows the	record size on a dataset to be
	   set larger than 128KB.

	   This	feature	becomes	active once a dataset contains a file  with  a
	   block size larger than 128KB, and will return to being enabled once
	   all filesystems that	have ever had  their  recordsize  larger  than
	   128KB are destroyed.

       large_dnode

	   GUID			  org.zfsonlinux:large_dnode
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   The	large_dnode  feature allows the	size of	dnodes in a dataset to
	   be set larger than 512B.

	   This	feature	becomes	active once a dataset contains an object  with
	   a  dnode  larger than 512B, which occurs as a result	of setting the
	   dnodesize dataset property to a value other than legacy.  The  fea-
	   ture	 will  return  to being	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.

       livelist

	   GUID			  com.delphix:livelist
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none
	   This	feature	allows clones to be deleted  faster  than  the	tradi-
	   tional 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 active	until all clones have been de-
	   stroyed.

       log_spacemap

	   GUID			  com.delphix:log_spacemap
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  com.delphix:spacemap_v2

	   This	feature	improves performance for heavily-fragmented pools, es-
	   pecially  when  workloads are heavy in random-writes. It does so by
	   logging all the metaslab changes on a single	spacemap every TXG in-
	   stead of scattering multiple	writes to all the metaslab spacemaps.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled.

       lz4_compress

	   GUID			  org.illumos:lz4_compress
	   READ-ONLY COMPATIBLE	  no

	   DEPENDENCIES		  none

	   lz4 is a high-performance real-time compression algorithm that fea-
	   tures significantly faster compression and decompression as well as
	   a higher compression	ratio than the older lzjb compression.	 Typi-
	   cally,  lz4 compression is approximately 50%	faster on compressible
	   data	and 200% faster	on incompressible data than lzjb. It  is  also
	   approximately  80%  faster  on decompression, while giving approxi-
	   mately 10% better compression ratio.

	   When	the lz4_compress feature is set	to enabled, the	 administrator
	   can	turn  on  lz4 compression on any dataset on the	pool using the
	   zfs(8) command. Please note that doing so will immediately activate
	   the	lz4_compress  feature  on the underlying pool using the	zfs(8)
	   command. Also, all newly written metadata will be  compressed  with
	   lz4 algorithm. Since	this feature is	not read-only compatible, this
	   operation will render the pool unimportable on systems without sup-
	   port	for the	lz4_compress feature.

	   Booting off of lz4-compressed root pools is supported.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled.

       multi_vdev_crash_dump

	   GUID			  com.joyent:multi_vdev_crash_dump
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  none

	   This	feature	allows a dump device to	be configured with a pool com-
	   prised  of multiple vdevs.  Those vdevs may be arranged in any mir-
	   rored or raidz configuration.

	   When	the multi_vdev_crash_dump feature is set to enabled,  the  ad-
	   ministrator can use the dumpadm(1M) command to configure a dump de-
	   vice	on a pool comprised of multiple	vdevs.

	   Under Linux this feature is registered for  compatibility  but  not
	   used.   New pools created under Linux will have the feature enabled
	   but will never transition to	active.	 This functionality is not re-
	   quired in order to support crash dumps under	Linux.	Existing pools
	   where this feature is active	can be imported.

       obsolete_counts

	   GUID			  com.delphix:obsolete_counts
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  device_removal

	   This	feature	is an enhancement of device_removal, which  will  over
	   time	 reduce	 the memory used to track removed devices.  When indi-
	   rect	blocks are freed or remapped, we note that their part  of  the
	   indirect mapping is "obsolete", i.e.	no longer needed.

	   This	 feature  becomes  active  when	the zpool remove subcommand is
	   used	on a top-level vdev, and will never return to being enabled.

       project_quota

	   GUID			  org.zfsonlinux:project_quota
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  extensible_dataset

	   This	feature	allows administrators to account the  spaces  and  ob-
	   jects usage information against the project identifier (ID).

	   The project ID is new object-based attribute. When upgrading	an ex-
	   isting filesystem, object without project ID	attribute will be  as-
	   signed a zero project ID. After this	feature	is enabled, newly cre-
	   ated	object will inherit its	parent directory's project ID  if  the
	   parent  inherit  flag  is  set  (via	 chattr	 +/-P  or  zfs project
	   [-s|-C]). Otherwise,	the new	object's project ID  will  be  set  as
	   zero. An object's project ID	can be changed at anytime by the owner
	   (or privileged user)	via chattr -p $prjid or	zfs project -p $prjid.

	   This	feature	will become active as soon as it is enabled  and  will
	   never  return  to  being disabled. Each filesystem will be upgraded
	   automatically when remounted	or when	new file is created under that
	   filesystem.	The  upgrade  can also be triggered on filesystems via
	   `zfs	set version=current <pool/fs>`.	 The upgrade process  runs  in
	   the background and may take a while to complete for the filesystems
	   containing a	large number of	files.

       redaction_bookmarks

	   GUID			  com.delphix:redaction_bookmarks
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  bookmarks, extensible_dataset

	   This	feature	enables	the use	of the redacted	 zfs  send.   Redacted
	   zfs	send  creates  redaction  bookmarks,  which  store the list of
	   blocks redacted by the send that created them.  For	more  informa-
	   tion	about redacted send, see zfs(8).

       redacted_datasets

	   GUID			  com.delphix:redacted_datasets
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   This	 feature  enables  the receiving of redacted zfs send streams.
	   Redacted zfs	send streams 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 receive, see zfs(8).

       resilver_defer

	   GUID			  com.datto:resilver_defer
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   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.

	   This	feature	becomes	active once a resilver has been	deferred,  and
	   returns to being enabled when the deferred resilver begins.

       sha512

	   GUID			  org.illumos:sha512
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   This	 feature enables the use of the	SHA-512/256 truncated hash al-
	   gorithm (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	impor-
	   tant, but these systems cannot  for	whatever  reason  utilize  the
	   faster skein	and edonr algorithms.

	   When	 the  sha512  feature is set to	enabled, the administrator can
	   turn	on the sha512 checksum on any dataset  using  zfs  set	check-
	   sum=sha512. See zfs(8). This	feature	becomes	active once a checksum
	   property has	been set to sha512, and	will return to	being  enabled
	   once	 all  filesystems  that	 have  ever  had their checksum	set to
	   sha512 are destroyed.

       skein

	   GUID			  org.illumos:skein
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   This	feature	enables	the use	of the Skein hash algorithm for	check-
	   sum	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.

	   When	 the  skein  feature  is set to	enabled, the administrator can
	   turn	on the skein checksum on any  dataset  using  zfs  set	check-
	   sum=skein.  See zfs(8). This	feature	becomes	active once a checksum
	   property has	been set to skein, and will return  to	being  enabled
	   once	all filesystems	that have ever had their checksum set to skein
	   are destroyed.

       spacemap_histogram

	   GUID			  com.delphix:spacemap_histogram
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   This	features allows	ZFS to maintain	 more  information  about  how
	   free	 space	is  organized  within the pool.	If this	feature	is en-
	   abled, ZFS will set this feature to active when a new space map ob-
	   ject	 is  created  or  an existing space map	is upgraded to the new
	   format. Once	the feature is active, it will remain  in  that	 state
	   until the pool is destroyed.

       spacemap_v2

	   GUID			  com.delphix:spacemap_v2
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   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.

	   This	 feature  becomes active once it is enabled, and never returns
	   back	to being enabled.

       userobj_accounting

	   GUID			  org.zfsonlinux:userobj_accounting
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  extensible_dataset

	   This	feature	allows administrators to account the object usage  in-
	   formation by	user and group.

	   This	feature	becomes	active as soon as it is	enabled	and will never
	   return to being enabled. Each filesystem will be upgraded automati-
	   cally  when	remounted,  or	when  new files	are created under that
	   filesystem.	The upgrade can	also be	started	manually  on  filesys-
	   tems	 by  running  `zfs set version=current <pool/fs>`. The upgrade
	   process runs	in the background and may take a while to complete for
	   filesystems containing a large number of files.

       zpool_checkpoint

	   GUID			  com.delphix:zpool_checkpoint
	   READ-ONLY COMPATIBLE	  yes
	   DEPENDENCIES		  none

	   This	 feature  enables  the	zpool  checkpoint  subcommand that can
	   checkpoint the state	of the pool at the  time  it  was  issued  and
	   later rewind	back to	it or discard it.

	   This	feature	becomes	active when the	zpool checkpoint subcommand is
	   used	to checkpoint the pool.	 The feature will only return back  to
	   being  enabled  when	the pool is rewound or the checkpoint has been
	   discarded.

       zstd_compress

	   GUID			  org.freebsd:zstd_compress
	   READ-ONLY COMPATIBLE	  no
	   DEPENDENCIES		  extensible_dataset

	   zstd	is a high-performance compression algorithm  that  features  a
	   combination	of high	compression ratios and high speed. Compared to
	   gzip, zstd offers slighty better compression	at much	higher speeds.
	   Compared  to	 lz4,  zstd offers much	better compression while being
	   only	modestly slower. Typically, zstd compression speed ranges from
	   250	to  500	MB/s per thread	and decompression speed	is over	1 GB/s
	   per thread.

	   When	the zstd feature is set	to enabled, the	administrator can turn
	   on  zstd  compression  of  any  dataset  by	running	 `zfs set com-
	   press=zstd <pool/fs>`.

	   This	feature	becomes	active once a compress property	has  been  set
	   to zstd, and	will return to being enabled once all filesystems that
	   have	ever had their compress	property set to	zstd are destroyed.

	   Booting off of zstd-compressed root pools is	not yet	supported.

SEE ALSO
       zpool(8)

				  Jun 8, 2018		     ZPOOL-FEATURES(5)

NAME | DESCRIPTION | FEATURES | SEE ALSO

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