Feature Flags

ZFS on-disk formats were originally versioned with a single number, which increased whenever the format changed. The numbered approach was suitable when development of ZFS was driven by a single organisation.

For distributed development of OpenZFS, version numbering was unsuitable. Any change to the number would have required agreement, across all implementations, of each change to the on-disk format.

OpenZFS feature flags – an alternative to traditional version numbering – allow a uniquely named pool property for each change to the on-disk format. This approach supports:

  • format changes that are independent

  • format changes that depend on each other.

Compatibility

Where all features that are used by a pool are supported by multiple implementations of OpenZFS, the on-disk format is portable across those implementations.

Features that are exclusive when enabled should be periodically ported to all distributions.

Reference materials

ZFS Feature Flags (Christopher Siden, 2012-01, in the Internet Archive Wayback Machine) in particular: “… Legacy version numbers still exist for pool versions 1-28 …”.

zpool-features(7) man page - OpenZFS

zpool-features (5) – illumos

Feature flags implementation per OS

ZFS Feature Matrix
Feature FlagRead-Only
Compatible
OpenZFS (Linux, FreeBSD 13+)FreeBSD pre OpenZFSIllumosJoyentNetBSDNexentaOmniOS CEOpenZFS on OS X
0.6.5.110.7.130.8.62.0.72.1.152.2.4master12.1.012.2.0mastermaster10.09.4main4.0.5-FPmasterr151048r151050master2.2.02.2.22.2.3rc4main
org.zfsonlinux:allocation_classesyesnonoyesyesyesyesyesnoyesyesyesnononononoyesyesyesyesyesyesyes
com.delphix:async_destroyyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
org.openzfs:blake3nonononononoyesyesnonononononononononononoyesyesyesyes
com.fudosecurity:block_cloningyesnononononoyesyesnonononononononononononoyesyesyesyes
com.datto:bookmark_v2nononoyesyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
com.delphix:bookmark_writtennonononoyesyesyesyesnonononononononononononoyesyesyesyes
com.delphix:bookmarksyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.nexenta:class_of_storageyesnonononononononononononononoyesyesnonononononono
org.openzfs:device_rebuildyesnononoyesyesyesyesnonononononononononononoyesyesyesyes
com.delphix:device_removalnononoyesyesyesyesyesyesyesyesyesnonononoyesyesyesyesyesyesyesyes
org.openzfs:draidnononononoyesyesyesnonononononononononononoyesyesyesyes
org.illumos:edonrnoyes1yes1yes1yes1yes1yes1yesnonoyesyesnonononoyesyesyesyesyesyesyesyes
com.delphix:embedded_datanoyesyesyesyesyesyesyesyesyesyesyesyesyesyesnoyesyesyesyesyesyesyesyes
com.delphix:empty_bpobjyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.delphix:enabled_txgyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.datto:encryptionnononoyesyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
com.delphix:extensible_datasetnoyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.joyent:filesystem_limitsyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.delphix:head_errlognonononononoyesyesnonononononononononononoyesyesyesyes
com.delphix:hole_birthnoyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
org.open-zfs:large_blocksnoyesyesyesyesyesyesyesyesyesyesyesyesyesyesnoyesyesyesyesyesyesyesyes
org.zfsonlinux:large_dnodenonoyesyesyesyesyesyesnoyesyesyesnononononoyesyesyesyesyesyesyes
com.delphix:livelistyesnononoyesyesyesyesnonononononononononononoyesyesyesyes
com.delphix:log_spacemapyesnononoyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
org.illumos:lz4_compressnoyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.nexenta:meta_devicesyesnonononononononononononononoyesyesnonononononono
com.joyent:multi_vdev_crash_dumpnonoyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.delphix:obsolete_countsyesnonoyesyesyesyesyesyesyesyesyesnonononoyesyesyesyesyesyesyesyes
org.zfsonlinux:project_quotayesnonoyesyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
org.openzfs:raidz_expansionnononononononoyesnononononononononononononoyesyesyes
com.delphix:redacted_datasetsnonononoyesyesyesyesnonononononononononononoyesyesyesyes
com.delphix:redaction_bookmarksnonononoyesyesyesyesnonononononononononononoyesyesyesyes
com.delphix:redaction_list_spillnononononononoyesnonononononononononononoyesyesyesyes
com.datto:resilver_deferyesnonoyesyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
org.illumos:sha512nonoyesyesyesyesyesyesyesyesyesyesyesyesyesnoyesyesyesyesyesyesyesyes
org.illumos:skeinnonoyesyesyesyesyesyesyesyesyesyesyesyesyesnoyesyesyesyesyesyesyesyes
com.delphix:spacemap_histogramyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyesyes
com.delphix:spacemap_v2yesnonoyesyesyesyesyesyesyesyesyesnononononoyesyesyesyesyesyesyes
org.zfsonlinux:userobj_accountingyesnoyesyesyesyesyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
com.nexenta:vdev_propertiesyesnonononononononononononononoyesyesnonononononono
com.klarasystems:vdev_zaps_v2nonononononoyesyesnonononononononononononoyesyesyesyes
com.nexenta:wbcnonononononononononononononononoyesnonononononono
org.openzfs:zilsaxattryesnononononoyesyesnonoyesyesnononononoyesyesyesyesyesyesyes
com.delphix:zpool_checkpointyesnonoyesyesyesyesyesyesyesyesyesnononononoyesyesyesyesyesyesyes
org.freebsd:zstd_compressnonononoyesyesyesyesnonononononononononononoyesyesyesyes

Table generates by parsing manpages for feature flags, and is entirely dependent on good, accurate documentation.
Last updated on 2024-06-04T09:28:28.380422Z using compatibility_matrix.py.