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I set up a ZFS pool of 8 harddrives under FreeBSD 7.2 a couple of years ago. This pool is storing data, the OS itself runs on a separate harddrive with conventional UFS2.

Now I am thinking about upgrading to the latest version FreeBSD 8.2.

Has anyone gone through upgrading ZFS before ? Can I simply export the pool in the 7 installation and then re-import in the new environment ? Or should I expect any complications ?

In other words: Are newer zpool versions backward compatible ?

FreeBSD 8.2 comes with ZFS version 15. I can't seem to find out what version came with 7.2, but IIRC, that was the first major release that supported it all...

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up vote 2 down vote accepted

An older pool can be imported with no issues on a newer system - it's completely backwards compatible.

However, it's not forward compatible; once you upgrade to version 15, there's no going back to an older system.

Use the zpool upgrade command to up the pool's version.

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thanks for the info! :-) I actually did assume ZFS is indeed backwards compatible, but I could not import the pools on the 8.x system, so I asked just to double-check. It seems however I can not import them on the original 7.2 system either, so the pools themselves are the root of the problem, not the new system. BTW: on the original 7.2 system: ZFS filesystem version 6, ZFS storage pool version 6 (just for completeness sake) – ssc Aug 3 '11 at 8:20

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