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diff --git a/usr/src/man/man5/zpool-features.5 b/usr/src/man/man5/zpool-features.5 deleted file mode 100644 index 38045f80df..0000000000 --- a/usr/src/man/man5/zpool-features.5 +++ /dev/null @@ -1,834 +0,0 @@ -'\" te -.\" Copyright (c) 2013, 2017 by Delphix. All rights reserved. -.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved. -.\" Copyright (c) 2014, Joyent, Inc. All rights reserved. -.\" Copyright (c) 2014 Integros [integros.com] -.\" 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] -.TH ZPOOL-FEATURES 5 "May 15, 2019" -.SH NAME -zpool\-features \- ZFS pool feature descriptions -.SH DESCRIPTION -.LP -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 \fBupgrade\fR subcommand of the -\fBzpool\fR(1M) command, or set the \fBfeature@\fR\fIfeature_name\fR property -to \fBenabled\fR. -.sp -.LP -The pool format does not affect file system version compatibility or the ability -to send file systems between pools. -.sp -.LP -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 -\fBactive\fR on the pool. If the pool was created by another software version -this set may include unsupported features. -.SS "Identifying features" -.LP -Every feature has a guid of the form \fIcom.example:feature_name\fR. The reverse -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. -.sp -.LP -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. -\fIcom.example:feature_name\fR would have the short name \fIfeature_name\fR), -however a feature's short name may differ across ZFS implementations if -following the convention would result in name conflicts. -.SS "Feature states" -.LP -Features can be in one of three states: -.sp -.ne 2 -.na -\fB\fBactive\fR\fR -.ad -.RS 12n -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"). -.RE - -.sp -.ne 2 -.na -\fB\fBenabled\fR\fR -.ad -.RS 12n -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 -\fBactive\fR state. Some features may support returning to the \fBenabled\fR -state after becoming \fBactive\fR. See feature\-specific documentation for -details. -.RE - -.sp -.ne 2 -.na -\fBdisabled\fR -.ad -.RS 12n -This feature's on\-disk format changes have not been made and will not be made -unless an administrator moves the feature to the \fBenabled\fR state. Features -cannot be disabled once they have been enabled. -.RE - -.sp -.LP -The state of supported features is exposed through pool properties of the form -\fIfeature@short_name\fR. -.SS "Read\-only compatibility" -.LP -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 -\fBreadonly\fR property during import (see \fBzpool\fR(1M) for details on -importing pools). -.SS "Unsupported features" -.LP -For each unsupported feature enabled on an imported pool a pool property -named \fIunsupported@feature_guid\fR will indicate why the import was allowed -despite the unsupported feature. Possible values for this property are: - -.sp -.ne 2 -.na -\fB\fBinactive\fR\fR -.ad -.RS 12n -The feature is in the \fBenabled\fR state and therefore the pool's on\-disk -format is still compatible with software that does not support this feature. -.RE - -.sp -.ne 2 -.na -\fB\fBreadonly\fR\fR -.ad -.RS 12n -The feature is read\-only compatible and the pool has been imported in -read\-only mode. -.RE - -.SS "Feature dependencies" -.LP -Some features depend on other features being enabled in order to function -properly. Enabling a feature will automatically enable any features it -depends on. -.SH FEATURES -.LP -The following features are supported on this system: -.sp -.ne 2 -.na -\fB\fBasync_destroy\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:async_destroy -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -Destroying a file system requires traversing all of its data in order to -return its used space to the pool. Without \fBasync_destroy\fR 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. - -When \fBasync_destroy\fR 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 \fBfreeing\fR property. - -This feature is only \fBactive\fR while \fBfreeing\fR is non\-zero. -.RE - -.sp -.ne 2 -.na -\fB\fBempty_bpobj\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:empty_bpobj -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -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 \fBactive\fR while there are any filesystems, volumes, -or snapshots which were created after enabling this feature. -.RE - -.sp -.ne 2 -.na -\fB\fBfilesystem_limits\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.joyent:filesystem_limits -READ\-ONLY COMPATIBLE yes -DEPENDENCIES extensible_dataset -.TE - -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 \fBactive\fR once either of the limit properties has been -set on a dataset. Once activated the feature is never deactivated. -.RE - -.sp -.ne 2 -.na -\fB\fBlz4_compress\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.illumos:lz4_compress -READ\-ONLY COMPATIBLE no -DEPENDENCIES none -.TE - -\fBlz4\fR 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 \fBlzjb\fR compression. -Typically, \fBlz4\fR compression is approximately 50% faster on -compressible data and 200% faster on incompressible data than -\fBlzjb\fR. It is also approximately 80% faster on decompression, while -giving approximately 10% better compression ratio. - -When the \fBlz4_compress\fR feature is set to \fBenabled\fR, the -administrator can turn on \fBlz4\fR compression on any dataset on the -pool using the \fBzfs\fR(1M) command. Also, all newly written metadata -will be compressed with \fBlz4\fR algorithm. Since this feature is not -read-only compatible, this operation will render the pool unimportable -on systems without support for the \fBlz4_compress\fR feature. Booting -off of \fBlz4\fR-compressed root pools is supported. - -This feature becomes \fBactive\fR as soon as it is enabled and will -never return to being \fBenabled\fR. -.RE - -.sp -.ne 2 -.na -\fB\fBspacemap_histogram\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:spacemap_histogram -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -This features allows ZFS to maintain more information about how free space -is organized within the pool. If this feature is \fBenabled\fR, ZFS will -set this feature to \fBactive\fR when a new space map object is created or -an existing space map is upgraded to the new format. Once the feature is -\fBactive\fR, it will remain in that state until the pool is destroyed. -.RE - -.sp -.ne 2 -.na -\fB\fBmulti_vdev_crash_dump\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.joyent:multi_vdev_crash_dump -READ\-ONLY COMPATIBLE no -DEPENDENCIES none -.TE - -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. - -When the \fBmulti_vdev_crash_dump\fR feature is set to \fBenabled\fR, -the administrator can use the \fBdumpadm\fR(1M) command to configure a -dump device on a pool comprised of multiple vdevs. -.RE - -.sp -.ne 2 -.na -\fB\fBextensible_dataset\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:extensible_dataset -READ\-ONLY COMPATIBLE no -DEPENDENCIES none -.TE - -This feature allows more flexible use of internal ZFS data structures, -and exists for other features to depend on. - -This feature will be \fBactive\fR when the first dependent feature uses it, -and will be returned to the \fBenabled\fR state when all datasets that use -this feature are destroyed. - -.RE - -.sp -.ne 2 -.na -\fB\fBbookmarks\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:bookmarks -READ\-ONLY COMPATIBLE yes -DEPENDENCIES extensible_dataset -.TE - -This feature enables use of the \fBzfs bookmark\fR subcommand. - -This feature is \fBactive\fR while any bookmarks exist in the pool. -All bookmarks in the pool can be listed by running -\fBzfs list -t bookmark -r \fIpoolname\fR\fR. - -.RE - -.sp -.ne 2 -.na -\fB\fBenabled_txg\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:enabled_txg -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -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. - -This feature becomes \fBactive\fR as soon as it is enabled and will -never return to being \fBenabled\fR. - -.RE - -.sp -.ne 2 -.na -\fB\fBhole_birth\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:hole_birth -READ\-ONLY COMPATIBLE no -DEPENDENCIES enabled_txg -.TE - -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 \fBA\fR to snapshot \fBB\fR -contains information about every block that changed between \fBA\fR and -\fBB\fR. 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 \fBA\fR cannot be -distinguished from holes created before \fBA\fR, 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 \fBhole_birth\fR 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. - -This feature becomes \fBactive\fR as soon as it is enabled and will -never return to being \fBenabled\fR. - -.RE - -.sp -.ne 2 -.na -\fB\fBembedded_data\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:embedded_data -READ\-ONLY COMPATIBLE no -DEPENDENCIES none -.TE - -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 compresseed 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 \fBactive\fR as soon as it is enabled and will -never return to being \fBenabled\fR. - -.RE -.sp -.ne 2 -.na -\fB\fBdevice_removal\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:device_removal -READ\-ONLY COMPATIBLE no -DEPENDENCIES none -.TE - -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 \fBactive\fR when the "zpool remove" command is used -on a top-level vdev, and will never return to being \fBenabled\fR. - -.RE -.sp -.ne 2 -.na -\fB\fBobsolete_counts\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:obsolete_counts -READ\-ONLY COMPATIBLE yes -DEPENDENCIES device_removal -.TE - -This feature is an enhancement of 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", i.e. no longer needed. See also the \fBzfs remap\fR -subcommand in \fBzfs\fR(1M). - -This feature becomes \fBactive\fR when the "zpool remove" command is -used on a top-level vdev, and will never return to being \fBenabled\fR. - -.RE -.sp -.ne 2 -.na -\fB\fBzpool_checkpoint\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:zpool_checkpoint -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -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 \fBactive\fR when the "zpool checkpoint" command -is used to checkpoint the pool. -The feature will only return back to being \fBenabled\fR when the pool -is rewound or the checkpoint has been discarded. - -.RE -.sp -.ne 2 -.na -\fB\fBspacemap_v2\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:spacemap_v2 -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -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 \fBactive\fR once it is \fBenabled\fR, and never -returns back to being \fBenabled\fR. - -.RE -.sp -.ne 2 -.na -\fB\fBlarge_blocks\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.open-zfs:large_block -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -The \fBlarge_block\fR feature allows the record size on a dataset to be -set larger than 128KB. - -This feature becomes \fBactive\fR once a \fBrecordsize\fR property has been -set larger than 128KB, and will return to being \fBenabled\fR once all -filesystems that have ever had their recordsize larger than 128KB are destroyed. -.RE - -.ne 2 -.na -\fB\fBlarge_dnode\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.zfsonlinux:large_dnode -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -The \fBlarge_dnode\fR feature allows the size of dnodes in a dataset to be -set larger than 512B. - -This feature becomes \fBactive\fR once a dataset contains an object with a -dnode larger than 512B, which occurs as a result of setting the \fBdnodesize\fR -dataset property to a value other than \fBlegacy\fR. The feature will return to -being \fBenabled\fR 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. -.RE - -.sp -.ne 2 -.na -\fB\fBsha512\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.illumos:sha512 -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -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 \fBskein\fR and -\fBedonr\fR algorithms. - -When the \fBsha512\fR feature is set to \fBenabled\fR, the administrator -can turn on the \fBsha512\fR checksum on any dataset using the -\fBzfs set checksum=sha512\fR command. This feature becomes -\fBactive\fR once a \fBchecksum\fR property has been set to \fBsha512\fR, -and will return to being \fBenabled\fR once all filesystems that have -ever had their checksum set to \fBsha512\fR are destroyed. - -Booting off of pools utilizing SHA-512/256 is supported. - -.RE - -.sp -.ne 2 -.na -\fB\fBskein\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.illumos:skein -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -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. - -When the \fBskein\fR feature is set to \fBenabled\fR, the administrator -can turn on the \fBskein\fR checksum on any dataset using the -\fBzfs set checksum=skein\fR command. This feature becomes -\fBactive\fR once a \fBchecksum\fR property has been set to \fBskein\fR, -and will return to being \fBenabled\fR once all filesystems that have -ever had their checksum set to \fBskein\fR are destroyed. - -Booting off of pools using \fBskein\fR is supported. - -.RE - -.sp -.ne 2 -.na -\fB\fBbookmark_v2\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.datto:bookmark_v2 -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -This feature enables the creation and management of larger bookmarks which are -needed for other features in ZFS. - -This feature becomes \fBactive\fR when a v2 bookmark is created and will be -returned to the \fBenabled\fR state when all v2 bookmarks are destroyed. - -.RE - -.sp -.ne 2 -.na -\fB\fBedonr\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.illumos:edonr -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -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 can not be used with dedup -(without verification). - -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. - -When the \fBedonr\fR feature is set to \fBenabled\fR, the administrator -can turn on the \fBedonr\fR checksum on any dataset using the -\fBzfs set checksum=edonr\fR command. This feature becomes -\fBactive\fR once a \fBchecksum\fR property has been set to \fBedonr\fR, -and will return to being \fBenabled\fR once all filesystems that have -ever had their checksum set to \fBedonr\fR are destroyed. - -Booting off of pools using \fBedonr\fR is supported. - -.RE - -.sp -.ne 2 -.na -\fB\fBallocation_classes\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.intel:allocation_classes -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -This feature enables support for separate allocation classes. - -This feature becomes \fBactive\fR when a dedicated allocation class vdev -(dedup or special) is created with zpool create or zpool add. With device -removal, it can be returned to the \fBenabled\fR state if all the top-level -vdevs from an allocation class are removed. -.RE - -.sp -.ne 2 -.na -\fB\fBencryption\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.datto:encryption -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset -.TE - -This feature enables the creation and management of natively encrypted datasets. - -This feature becomes \fBactive\fR when an encrypted dataset is created -and will be returned to the \fBenabled\fR state when all datasets that -use this feature are destroyed. - -.RE -.sp -.ne 2 -.na -\fB\fBresilver_defer\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.datto:resilver_defer -READ\-ONLY COMPATIBLE yes -DEPENDENCIES none -.TE - -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 \fBactive\fR once a resilver has been deferred, and -returns to being \fBenabled\fR when the deferred resilver begins. -.RE - -.sp -.ne 2 -.na -\fBuserobj_accounting\fR -.ad -.RS 4n -.TS -l l . -GUID org.zfsonlinux:userobj_accounting -READ\-ONLY COMPATIBLE yes -DEPENDENCIES extensible_dataset -.TE - -This feature allows administrators to account the object usage information -by user and group. - -This feature becomes \fBactive\fR as soon as it is enabled and will never -return to being \fBenabled\fR. -Each filesystem will be upgraded automatically when remounted, or when new -files are created under that filesystem. -The upgrade can also be started manually on filesystems 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. -.RE - -.sp -.ne 2 -.na -\fBproject_quota\fR -.ad -.RS 4n -.TS -l l . -GUID org.zfsonlinux:project_quota -READ\-ONLY COMPATIBLE yes -DEPENDENCIES extensible_dataset -.TE - -This feature allows administrators to account the space and object usage -information against the project identifier (ID). - -The project ID is a new object-based attribute. -When upgrading an existing filesystem, an object without a project ID -attribute will be assigned a zero project ID. -After this feature is enabled, a newly created object will inherit -its parent directory's project ID if the parent's inherit flag is set (via -\fBzfs project [-s|-C]\fR). -Otherwise, the new object's project ID will be set as zero. -An object's project ID can be changed at any time by the owner (or privileged -user) via \fBzfs project -p $prjid\fR. - -This feature will become \fBactive\fR as soon as it is enabled and will never -return to being \fBdisabled\fR. -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 `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. -.RE - -.sp -.ne 2 -.na -\fBlog_spacemap\fR -.ad -.RS 4n -.TS -l l . -GUID com.delphix:log_spacemap -READ\-ONLY COMPATIBLE yes -DEPENDENCIES com.delphix:spacemap_v2 -.TE - -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. - -This feature becomes \fBactive\fR as soon as it is enabled and will never -return to being \fBenabled\fR. -.RE - -.SH "SEE ALSO" -\fBzfs\fR(1M), \fBzpool\fR(1M) |