diff --git a/man/man5/zpool-features.5 b/man/man5/zpool-features.5 index 78c778da5..5a997b893 100644 --- a/man/man5/zpool-features.5 +++ b/man/man5/zpool-features.5 @@ -142,6 +142,28 @@ depends on. .sp .LP The following features are supported on this system: + +.sp +.ne 2 +.na +\fB\fBallocation_classes\fR\fR +.ad +.RS 4n +.TS +l l . +GUID org.zfsonlinux: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 the \fBzpool create\fR or \fBzpool add\fR +subcommands. With device removal, it can be returned to the \fBenabled\fR +state if all the dedicated allocation class vdevs are removed. +.RE + .sp .ne 2 .na @@ -172,6 +194,133 @@ through the \fBfreeing\fR property. This feature is only \fBactive\fR while \fBfreeing\fR is non\-zero. .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\fBbookmark_v2\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.datto:bookmark_v2 +READ\-ONLY COMPATIBLE no +DEPENDENCIES bookmark, 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\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 \fBzpool remove\fR subcommand to remove top-level +vdevs, evacuating them to reduce the total size of the pool. + +This feature becomes \fBactive\fR when the \fBzpool remove\fR subcommand is used +on a top-level vdev, and will never return to being \fBenabled\fR. +.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 requires verification when used with +dedup: \fBzfs set dedup=edonr,verify\fR. See \fBzfs\fR(8). + +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. See zfs(8). 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. + +The \fBedonr\fR feature is not supported by GRUB and must not be used on +the pool if GRUB needs to access the pool (e.g. for /boot). +.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 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 \fBactive\fR as soon as it is enabled and will +never return to being \fBenabled\fR. +.RE + .sp .ne 2 .na @@ -202,55 +351,19 @@ or snapshots which were created after enabling this feature. .sp .ne 2 .na -\fB\fBfilesystem_limits\fR\fR +\fB\fBenabled_txg\fR\fR .ad .RS 4n .TS l l . -GUID com.joyent:filesystem_limits +GUID com.delphix:enabled_txg 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 zfs(8) command. Please note that doing so will -immediately activate the \fBlz4_compress\fR feature on the underlying -pool using the zfs(8) 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. +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\fB. @@ -259,49 +372,21 @@ never return to being \fBenabled\fB. .sp .ne 2 .na -\fB\fBspacemap_histogram\fR\fR +\fB\fBencryption\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 +GUID com.datto:encryption READ\-ONLY COMPATIBLE no -DEPENDENCIES none +DEPENDENCIES bookmark_v2, extensible_dataset .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. +This feature enables the creation and management of natively encrypted datasets. -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. - -Under Linux this feature is registered for compatibility but not used. -New pools created under Linux will have the feature \fBenabled\fR but -will never transition to \fB\fBactive\fR. This functionality is not -required in order to support crash dumps under Linux. Existing pools -where this feature is \fB\fBactive\fR can be imported. +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 @@ -328,42 +413,22 @@ this feature are destroyed. .sp .ne 2 .na -\fB\fBbookmarks\fR\fR +\fB\fBfilesystem_limits\fR\fR .ad .RS 4n .TS l l . -GUID com.delphix:bookmarks +GUID com.joyent:filesystem_limits READ\-ONLY COMPATIBLE yes DEPENDENCIES extensible_dataset .TE -This feature enables use of the \fBzfs bookmark\fR subcommand. +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 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\fB. +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 @@ -415,121 +480,6 @@ This feature becomes \fBactive\fR as soon as it is enabled and will never return to being \fBenabled\fB. .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 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 \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 \fBzpool remove\fR subcommand to remove top-level -vdevs, evacuating them to reduce the total size of the pool. - -This feature becomes \fBactive\fR when the \fBzpool remove\fR subcommand 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. - -This feature becomes \fBactive\fR when the \fBzpool remove\fR subcommand 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 \fBzpool checkpoint\fR 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 \fBzpool checkpoint\fR subcommand -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 @@ -576,6 +526,146 @@ 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\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 zfs(8) command. Please note that doing so will +immediately activate the \fBlz4_compress\fR feature on the underlying +pool using the zfs(8) 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\fB. +.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. + +Under Linux this feature is registered for compatibility but not used. +New pools created under Linux will have the feature \fBenabled\fR but +will never transition to \fB\fBactive\fR. This functionality is not +required in order to support crash dumps under Linux. Existing pools +where this feature is \fB\fBactive\fR can be imported. +.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. + +This feature becomes \fBactive\fR when the \fBzpool remove\fR subcommand is +used on a top-level vdev, and will never return to being \fBenabled\fR. +.RE + +.sp +.ne 2 +.na +\fB\fBproject_quota\fR\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 spaces and objects usage +information against the project identifier (ID). + +The project ID is new object-based attribute. When upgrading an existing +filesystem, object without project ID attribute will be assigned a zero +project ID. After this feature is enabled, newly created object will inherit +its parent directory's project ID if the parent inherit flag is set (via +\fBchattr +/-P\fR or \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 +anytime by the owner (or privileged user) via \fBchattr -p $prjid\fR or +\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 new file is created under that filesystem. The upgrade +can also be triggered on filesystems via `zfs set version=current `. +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 +\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 @@ -645,41 +735,44 @@ the pool if GRUB needs to access the pool (e.g. for /boot). .sp .ne 2 .na -\fB\fBedonr\fR\fR +\fB\fBspacemap_histogram\fR\fR .ad .RS 4n .TS l l . -GUID org.illumos:edonr -READ\-ONLY COMPATIBLE no -DEPENDENCIES extensible_dataset +GUID com.delphix:spacemap_histogram +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none .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 requires verification when used with -dedup: \fBzfs set dedup=edonr,verify\fR. See \fBzfs\fR(8). +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 -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. +.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 -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. See zfs(8). 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. +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. -The \fBedonr\fR feature is not supported by GRUB and must not be used on -the pool if GRUB needs to access the pool (e.g. for /boot). +This feature becomes \fBactive\fR once it is \fBenabled\fR, and never +returns back to being \fBenabled\fR. .RE .sp @@ -710,116 +803,24 @@ files. .sp .ne 2 .na -\fB\fBbookmark_v2\fR\fR +\fB\fBzpool_checkpoint\fR\fR .ad .RS 4n .TS l l . -GUID com.datto:bookmark_v2 -READ\-ONLY COMPATIBLE no -DEPENDENCIES bookmark, 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\fBencryption\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.datto:encryption -READ\-ONLY COMPATIBLE no -DEPENDENCIES bookmark_v2, 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\fBproject_quota\fR\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 spaces and objects usage -information against the project identifier (ID). - -The project ID is new object-based attribute. When upgrading an existing -filesystem, object without project ID attribute will be assigned a zero -project ID. After this feature is enabled, newly created object will inherit -its parent directory's project ID if the parent inherit flag is set (via -\fBchattr +/-P\fR or \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 -anytime by the owner (or privileged user) via \fBchattr -p $prjid\fR or -\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 new file is created under that filesystem. The upgrade -can also be triggered on filesystems via `zfs set version=current `. -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 -\fB\fBresilver_defer\fR\fR -.ad -.RS 4n -.TS -l l . -GUID com.datto:resilver_defer +GUID com.delphix:zpool_checkpoint 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 enables the \fBzpool checkpoint\fR 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 once a resilver has been deferred, and -returns to being \fBenabled\fR when the deferred resilver begins. -.RE - -.sp -.ne 2 -.na -\fB\fBallocation_classes\fR\fR -.ad -.RS 4n -.TS -l l . -GUID org.zfsonlinux: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 the \fBzpool create\fR or \fBzpool add\fR -subcommands. With device removal, it can be returned to the \fBenabled\fR -state if all the dedicated allocation class vdevs are removed. +This feature becomes \fBactive\fR when the \fBzpool checkpoint\fR subcommand +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 .SH "SEE ALSO"