[OpenIndiana-discuss] Mixing zfs raids and mirrors

[James Carlson]

Gabriele Bulfon wrote:
> Hi,
> I was wondering what (if any) problems I may encounter by mixing different zfs strategies on one pool,
> with all equal disk sizes.
> Examples:
> - pool1: raidz1 a0 a1 a2 mirror a3 a4
> - pool2: raidz1 b0 b1 b2 raidz1 b3 b4 b5 mirror b6 b7
> - pool3: mirror c0 c1 mirror c2 c3 raidz c4 c5 c6
> I'm just trying to balance pools performance and maximum space...
> Last but not least:
> - what if pool3 is actually the rpool (where system just occupies few GBytes), where I'll add
> volumes with quotas to share? Should I keep rpool separate absolutely?
> (I just don't want to miss many GB on an rpool that will just stay as it is, on the boot disks).

Last I checked, it wasn't possible to boot off of RAID-Z; only mirrors
were supported for boot.  As for the other part, the man page says:

     Virtual devices cannot be nested, so a mirror or raidz  vir-
     tual device can only contain files or disks. Mirrors of mir-
     rors (or other combinations) are not allowed.

If you're looking to boost RAID-Z performance, I'd suggest adding more
disks.  RAID-Z will effectively stripe the data across the available
devices, parallelizing the I/O operations.  To get better error
tolerance, use raidz2 or raidz3.

-- 
James Carlson         42.703N 71.076W         <carlsonj at workingcode.com>