9.3 update smooth as butter - but I have questionw about ZFS version

[pschatz100]

I just updated my system to 9.3 stable and everything went fine. However, the alert button is flashing yellow because I did not update the ZFS version. I plan to keep the current ZFS version in order to maintain backward compatibility with some other systems (and this is the default behavior of the updater.)

Questions:
1) If I create a new ZFS volume, will it be the same as my current version or will it be the newer version?
2) Is there any compelling reason to update the ZFS version?

 

[pschatz100]

I just discovered that one can clear the check box on the ZFS version warning, and that will prevent the alert button from flashing yellow.

 

[SirMaster]

It's not really the version updating. OpenZFS is frozen on v5000 and changes are done via feature flags. FreeNAS wants to enable every available feature flag automatically but it's not necessary if you don't want them.

The feature flag that was added in the OpenZFS code that was updated in 9.3 adds 1 new feature flag called embedded_data.

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 active as soon as it is enabled and will never return to being enabled.

It's a pretty nifty feature if you use compression (which most people should be and is the default in FreeNAS). Whether or not your personal data is composed of very many highly-compressible blocks just depends on your data.

It's also worth noting that all the OpenZFS implementations support this flag. You will be able to import a FreeNAS 9.3 pool in Illumos, BSD, Linux, and OSX. You just won't be able to import it into older versions of FreeNAS or the current FreeBSD RELEASE branch, but CURRENT will work, not sure about STABLE, but I think it has it.

 

[pschatz100]

@SirMaster: Thanks for your explanation. I plan to wait a few weeks to make certain everything works OK, then I'll update the filesystem. I feel much better knowing the feature is widely supported.

 

[cyberjock]

@SirMaster: Thanks for your explanation. I plan to wait a few weeks to make certain everything works OK, then I'll update the filesystem. I feel much better knowing the feature is widely supported.

This is exactly what I do. I install an update to FreeNAS and wait a few weeks. If after a few weeks I haven't been forced to rollback for some reason then I do a zpool upgrade. ;)