[zfs-discuss] zpools with odd numbers of mirrors

Brian Behlendorf behlendorf1 at llnl.gov
Tue May 29 12:21:23 EDT 2012

I've never benchmarked this.  But performance should only increase as
you add mirror pairs to your pool.  Your going to be writing 128k block
to both sides of the mirror regardless of how many pairs their are.


On Tue, 2012-05-29 at 05:59 -0700, Marcus Sorensen wrote:
> This is more of a general zfs question. I'm wondering if there's any
> strong preference or advantage to staying on powers of two for number
> of mirrors in a zpool. I've got two external storage chassis that I
> want to mirror, and due to the number of disks and my preference of
> breaking them up into separate zpools, it seems like the most
> efficient setup would be a few zpools of 7 mirrors (14 disks). I can
> do 8 mirrors, but it leaves me with more empty slots and I may end up
> having to expand to 9 mirrors or something like that anyway. I'm using
> zvols, so it would leave me with a 56k or 112k full stripe instead of
> 64k or 128k, depending on the zvol blocksize I choose. I know ZFS is
> designed to handle this, but what about performance? Is it going to be
> doing a lot of work splitting IOs or something?

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