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Comment by stiray | Hacker News Reader

What really worries me here is compatibility with older pools.I hope they have thought about that as freebsd implementation is here since 2007.

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ZFS has feature flags [1]. If you're carefull not to do 'zpool upgrade' (as this commit message warns) unless you understand the consequences, you can switch between ZFS implementations.

[1] http://build.zfsonlinux.org/zfs-features.html

You can explicity create a pool with certain features disabled.

I'm going to try FreeNAS Core tonight.

It's my understanding that ZFS is backwards compatible forever; old pools are on old versions or have fewer feature flags, but they can still be used without issue.

Yes in theory they are but currently syncing pools between linux and freebsd zfs is not possible so I would imagine there are some differences. I have around 12Tb of zraided disk space on freebsd and I hope I will be able to upgrade eventually.

About 2 years ago, I shared a zpool between Linux, FreeBSD, and SmartOS/Illumos. It generally just worked, no matter where the zpool was created from. People warned me about not enabling specific features, so I simply used defaults to see what would happen. Again, 2 years ago, it just worked.

Eh? I currently share a zpool between linux and freebsd, and it works fine without issue.

Thank you for the info, I wasn't aware of that, the last time I have tryed it didt work (1-2 years back)

ZFS is backwards compatible, not forwards compatible.

If you create the pool on pre-OpenZFS FreeBSD, you can use it on Linux, but not vice versa.

I just did this with FreeNAS (based on FreeBSD 11) and Raspbian.

If you leave "zpool create" to its defaults (enable every feature).

There's two levels to consider though if you create a pool with explicit consideration for a system with an older version of ZFS: "-o version" and "-d"/"-o feature@...", both of which can be used to fine tune exactly what the pool can and cannot do.

I've made a list to help out doing it between ZFS-on-Linux releases. It shouldn't be hard to look up FreeBSD feature lists and do the same: https://chungy.keybase.pub/zfs-features-table.html

But if you create the zfs with openzfs on freebsd it's the same version and works:

sysutils/openzfs/

Yes they care about that, with the pool and filesystem versioning, Michael W. Lucas talks about that in this vid:

https://www.youtube.com/watch?v=gmaHZBwDKho

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