ZFS - thanks

[Freddie Cash]

On Sat, Jul 11, 2009 at 1:40 AM, Peter Jeremy
<peterjeremy at optushome.com.au>wrote:

> On 2009-Jul-09 15:39:35 +0300, Dan Naumov <dan.naumov at gmail.com> wrote:
> >A single 40 disk raidz (DO NOT DO THIS) will have 40 disks total, 39
> >disks worth of space and will definately explode on you sooner rather
> >than later (probably on the first import, export or scrub).
>
> Can you provide a reference for this statement.  AFAIK, the only
> reason for the upper recommended limit of 9 disks is performance.
>

We found it impossible to re-silver a new/replacement drive in a 24-drive
raidz2 vdev.  Even after almost two weeks of trying, it never got above
20-30% complete before restarting.

That led me to do a bunch of web searches, and found several blogs by Sun
people that went over how the raidz implementation works, what the
limitations are (limited to the IOps of a single drive), and the
recommendation to never use more than 8 or 9 drives in any single vdev.

-- 
Freddie Cash
fjwcash at gmail.com