ZfS & GEOM with many odd drive sizes

Mark Powell M.S.Powell at salford.ac.uk
Wed Jul 25 09:23:50 UTC 2007

On Sat, 21 Jul 2007, Pawel Jakub Dawidek wrote:

Thanks for your reply.

> Be sure to turn off debugging, ie. remove WITNESS, INVARIANTS and
> INVARIANT_SUPPORT options from your kernel configuration.
> Other than that, ZFS may just be more CPU hungry...

   I have. Makes little difference. Think the idea of using an Athlon XP 
for ZFS has turned out to be a bridge too far. The new 65nm Athlon 64 x2 
are very cheap now. Time for an upgrade.
   You said that replacing one device with another is not a problem. Just 
to be clear on this as it's a key factor in me going with this solution. I 
hope this isn't too naive a question, but the answer will be here for 
others :)
   Suppose instead of gconcat I used gstripe on the 250+200 combinations:

i.e. (slice 1 on all drives is reserved for ufs gmirror of /boot and 
block device swap)

gs0 ad0s2 ad1s2
gs1 ad2s2 ad3s2
gs2 ad4s2 ad5s2

I use these gstripes and the single 400GB drive to construct the zpool:

zpool create tank raidz /dev/mirror/gs0 /dev/mirror/gs1 /dev/mirror/gs2 ad6s2

If for example ad3 fails and thus gs1 fails, how is this replaced in the 
zpool? e.g. suppose I replace both ad2 and ad3 with a new 500GB drive as 
ad2. Is fixing this as simple as:

zpool replace tank /dev/mirror/gs1 ad2s2

Many thanks.

Mark Powell - UNIX System Administrator - The University of Salford
Information Services Division, Clifford Whitworth Building,
Salford University, Manchester, M5 4WT, UK.
Tel: +44 161 295 4837  Fax: +44 161 295 5888  www.pgp.com for PGP key

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