Difference between revisions of "Feature Flags"
Grahamperrin (talk | contribs) m (Oops; not Oracle.) |
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|- | |- | ||
| | | | ||
| | | 10.3 | ||
| | | 11.0 | ||
| | | stable/11 | ||
| | | r313645 | ||
| 0.6.5 | | 0.6.5 | ||
| 1.4.5 | | 1.4.5 | ||
Line 68: | Line 68: | ||
|- | |- | ||
!multi_vdev_crash_dump | !multi_vdev_crash_dump | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 77: | Line 77: | ||
|- | |- | ||
!spacemap_histogram | !spacemap_histogram | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 86: | Line 86: | ||
|- | |- | ||
!enabled_txg | !enabled_txg | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 95: | Line 95: | ||
|- | |- | ||
!hole_birth | !hole_birth | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 104: | Line 104: | ||
|- | |- | ||
!extensible_dataset | !extensible_dataset | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 113: | Line 113: | ||
|- | |- | ||
!embedded_data | !embedded_data | ||
| | |style="background-color:lightgreen"|yes | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 122: | Line 122: | ||
|- | |- | ||
!bookmarks | !bookmarks | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 131: | Line 131: | ||
|- | |- | ||
!filesystem_limits | !filesystem_limits | ||
| | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
Line 140: | Line 140: | ||
|- | |- | ||
!large_blocks | !large_blocks | ||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|style="background-color:lightgreen"|yes | |||
|- | |||
!sha512 | |||
|no | |no | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |||
|?? | |||
|?? | |||
|?? | |||
|- | |||
!skein | |||
|no | |||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|style="background-color:lightgreen"|yes | |style="background-color:lightgreen"|yes | ||
|?? | |||
|?? | |||
|?? | |||
|} | |} | ||
Revision as of 19:58, 18 February 2017
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(5) – illumos
zpool-features(7) – FreeBSD
Feature flags implementation
Feature flag | FreeBSD | ZFS on Linux | OpenZFS OSX | OmniOS | |||
---|---|---|---|---|---|---|---|
10.3 | 11.0 | stable/11 | r313645 | 0.6.5 | 1.4.5 | r151014 | |
async_destroy | yes | yes | yes | yes | yes | yes | yes |
empty_bpobj | yes | yes | yes | yes | yes | yes | yes |
lz4_compress | yes | yes | yes | yes | yes | yes | yes |
multi_vdev_crash_dump | yes | yes | yes | yes | no | no | yes |
spacemap_histogram | yes | yes | yes | yes | yes | yes | yes |
enabled_txg | yes | yes | yes | yes | yes | yes | yes |
hole_birth | yes | yes | yes | yes | yes | yes | yes |
extensible_dataset | yes | yes | yes | yes | yes | yes | yes |
embedded_data | yes | yes | yes | yes | yes | yes | yes |
bookmarks | yes | yes | yes | yes | yes | yes | yes |
filesystem_limits | yes | yes | yes | yes | yes | yes | yes |
large_blocks | yes | yes | yes | yes | yes | yes | yes |
sha512 | no | yes | yes | yes | ?? | ?? | ?? |
skein | no | yes | yes | yes | ?? | ?? | ?? |
Table legend
- no = not implemented
- yes = implemented
Source: OpenZFS Feature Flags Compatibility Matrix - VX weblog