zfs discuss - May 2006 - ZFS v2 backward compatible: ZFS pools <b38 importable in b38 or newer?

Could anyone confirm that with the recent additions to ZFS, most notably ZFS
version 2, that a ZFS pool created in b37 or older will still be
readable/importable in b38 ZFS version 2 and newer?

If so, is there any serious negative impact on the using an existing ZFS pool or
should the older pool be destroyed and recreated?

Of course I understand the data backup mantras, but these answers would be a
huge time-saver for restoring after the next upgrade.

Thanks.
 
 
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Wes Williams wrote:
> Could anyone confirm that with the recent additions to ZFS, most notably
ZFS version 2, that a ZFS pool created in b37 or older will still be
readable/importable in b38 ZFS version 2 and newer?
> 
> If so, is there any serious negative impact on the using an existing ZFS
pool or should the older pool be destroyed and recreated?
> 
> Of course I understand the data backup mantras, but these answers would be
a huge time-saver for restoring after the next upgrade.
It will be usable but you won''t get the version 2 features.

More importantly though you can upgrade to version 2 online it it only 
takes seconds (maybe less).

See the upgrade command of zfs(1).


-- 
Darren J Moffat

On Mon, May 22, 2006 at 07:19:30AM -0700, Wes Williams
wrote:
> Could anyone confirm that with the recent additions to ZFS, most
> notably ZFS version 2, that a ZFS pool created in b37 or older will
> still be readable/importable in b38 ZFS version 2 and newer?
Yes.  If you do not do an explicit "zpool upgrade", the pool will
continue to be written as version 1, and will still be readable on older
versions of the software.  Once you do a "zpool upgrade", you
won''t be
able to access the pool from earlier releases.
> If so, is there any serious negative impact on the using an existing
> ZFS pool or should the older pool be destroyed and recreated?
The only negative impact of using a version 1 pool is that you can''t
take advantage of ditto blocks (metadata replication).  Unless you want
to access the pool from older hosts, it is recommended that use ''zpool
upgrade''.  This will turn on metadata replication for subsequent
writes.
If you want to be sure that you have all possible ditto blocks, you
would have to destroy and recreate the pool.

- Eric

--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock

Thank you gentlemen for your quick replies. 

The ZFS upgrade process sounds like it''ll be a snap since I''ll
simply use the native ZFS version 2 on my next install/upgrade and simply import
my data from the existing backup pools (prior to ZFS v2).

Keep up the great work!
 
 
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