ZfS & GEOM with many odd drive sizes

[Pawel Jakub Dawidek]

On Thu, Jul 19, 2007 at 11:19:08AM +0100, Mark Powell wrote:
> Hi,
>   I'd like to experiment with ZFS.
>   To that end I'd like to get a running array from a rather ad hoc 
> collection of old drives.
> 
>  3x250GB
>  3x200GB
>  1x400GB
> 
> 
> I planned to arrange them in 3 pairs of of 250+200. Therefore I'd end up 
> with an effective 4 drives:
> 
>  3x450GB
>  1x400GB
> 
> I'd gmirror to make a small 2GB root and swap from the extra 50GB on the 3 
> pairs. Then gconcat to join the remaining 448GB from each pair into a 
> volume. Apparently root is possible on ZFS with a small ufs to boot from:
> 
> http://wiki.freebsd.org/ZFSOnRoot
> 
>   Then make a zfs raidz from the 3x448+1x400. Effectively giving a zpool 
> of 1200GB real storage. 3x48GB will not be accessible now as the last 
> volume will only be the 400GB on the last drive.
>   I want to be able to increase the size of this volume later, by 
> replacing drives when they fail, or it becomes economical to do so.
>   I know removing a volume from a zpool and replacing it with a larger one 
> is possible. The zpool will self-heal the data onto the new volume. 
> Eventually when the final volume is replaced by a larger one the extra 
> space becomes available for use. That's correct right?
>   What I want to know is, does the new volume have to be the same actual 
> device name or can it be substituted with another?
>   i.e. can I remove, for example, one of the 448GB gconcats e.g. gc1 and 
> replace that with a new 750GB drive e.g. ad6?
>   Eventually so that once all volumes are replaced the zpool could be, for 
> example, 4x750GB or 2.25TB of usable storage.
>   Many thanks for any advice on these matters which are new to me.

All you described above should work.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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