ZFS ZFS - snapshots and pool versions

chrbr

chrbr

Dear FreeBSD-Community,

currently there is a lot of activity related to ZFS. Regarding the versions of FreeBSD there are installations of FreeBSD-12.4 where the well known ZFS is still alive. With FreeBSD-13.x the switch to Open-ZFS has been made. FreeBSD-14.0 adds additional properties or features to ZFS pools.

Is there any effect on the transfer and the access to snapshots? Can I send a snapshot of a FreeBSD-12.4 pool using zfs send and receive it with zfs receive on FreeBSD-14.0 on a pool with additional properties enabled? How about the other way around from a "new" FreeBSD to and "old" one?

Usually I can restore a snapshot and have the content of the file system similar to the time when the snapshot has been taken. If the transfer of a snapshot is possible can I restore it, even if the snapshot has been taken from a pool with more or less properties available?

It might also be that the snapshot handling is independent from the versions of the involved pools, but may be not. Thank you in advance for your help.

Kind regards,
Christoph
 
zpool-features.7 — OpenZFS documentation

chrbr said:
… Can I send a snapshot of a FreeBSD-12.4 pool using zfs send and receive it with zfs receive on FreeBSD-14.0 on a pool with additional properties enabled?
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I believe so.

How about the other way around from a "new" FreeBSD to and "old" one? …
Click to expand...

Depending on the pool feature, and whether it's enabled or active: you might find that an upgraded pool can not be used with a version of FreeBSD that does not support the feature.
 
jb1277976 said:
Speaking of versions. Will freeBSD upgrade to openzfs eventually and if so how do we update? I been on zfs and learning so I'm was just wondering
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You've missed the OP's remark about this:
chrbr said:
[...] With FreeBSD-13.x the switch to Open-ZFS has been made. FreeBSD-14.0 adds additional properties or features to ZFS pools.
Click to expand...

You may have come across statements like:
  • "FreeBSD-ZFS uses the original Solaris ZFS"
    regarding FreeBSD with its ZFS codebase pre-OpenZFS
  • "FreeBSD-ZFS is Linux ZFS or ZoL"
    regarding FreeBSD with its ZFS codebase based on OpenZFS version 2 and higher
Such statements are inaccurate or even plainly wrong.

Currently the only supported FreeBSD versions where its ZFS code base is pre-OpenZFS are 12.4-RELEASE and 12-STABLE. As we're counting down the days towards 2024, support for these versions ends when FreeBSD 12 becomes EoL at the end of 2023.

When Solaris (ZFS included) was open sourced, Illumos (forked from open sourced Solaris) became its open source successor. From that moment on and from 2013 onwards there have been three different "code flow" periods regarding the development of open source ZFS code.

As OpenZFS functions as a central hub for all open source ZFS development, it is good to know a bit more about the OpenZFS initiative in general and more specifically about the mentioned "ZFS code flow"; see my earlier write-up here. For FreeBSD, from a feature flags point of view, you can view the difference in supported feature flags in the columns OpenZFS (Linux, FreeBSD 13+) versus FreeBSD pre OpenZFS.
 
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