Difference between revisions of "Features"

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== Feature Flags ==
== Feature Flags ==


See these [http://blog.delphix.com/csiden/files/2012/01/ZFS_Feature_Flags.pdf slides (Jan 2012)] for more details.
Originally the ZFS on-disk format was versioned with a single number which was increased whenever a new on-disk format change was introduced. This worked well when a single entity controlled the development of ZFS; however, in the more distributed development model of OpenZFS a single version number is not ideal. Every OpenZFS implementation would need to agree on every change to the on-disk format.
 
One of the first OpenZFS projects was a new versioning system called "feature flags" which tags on-disk format changes with unique names. The system supports both completely independent format changes, as well as format changes that depend on each other. A pool's on-disk format is portable between OpenZFS implementations as long as all of the feature flags in use by the pool are supported by both implementations.
 
All OpenZFS implementations now support feature flags and regularly port features between them to remain compatible.
 
{| class="wikitable"
|
| '''illumos'''
| '''FreeBSD'''
| '''ZFS on Linux'''
| '''Mac ZFS'''
|-
| '''async_destroy'''
| Y
| Y
| Y
| Y
|-
| '''empty_bpobj'''
| Y
| ?
| ?
| ?
|-
| '''lz4_compress'''
| Y
| ?
| ?
| ?
|}
 
For more details see these [http://blog.delphix.com/csiden/files/2012/01/ZFS_Feature_Flags.pdf slides (Jan 2012)] and <tt>zpool-features(5)</tt>.


== libzfs_core ==
== libzfs_core ==
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