zfs discuss - Apr 2010 - Question about large pools

Hi all
>From http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide
I read
"Avoid creating a RAIDZ, RAIDZ-2, RAIDZ-3, or a mirrored configuration with
one logical device of 40+ devices. See the sections below for examples of
redundant configurations."

What do they mean by this? 40+ devices in a single raidz[123] set or 40+ devices
in a pool regardless of raidz[123] sets?

Best regards

roy

On 02/04/2010 05:45, Roy Sigurd Karlsbakk wrote:
> Hi all
>
> > From
http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide I read
>
> "Avoid creating a RAIDZ, RAIDZ-2, RAIDZ-3, or a mirrored configuration
with one logical device of 40+ devices. See the sections below for examples of
redundant configurations."
>
> What do they mean by this? 40+ devices in a single raidz[123] set or 40+
devices in a pool regardless of raidz[123] sets?
>
>    
It means - try to avoid a single RAID-Z group with 40+ disk drives.
Creating several smaller groups in a one pool is perfectly fine.

So for example - on x4540 servers try to avoid creating a pool with a 
single RAID-Z3 group made of 44 disks, rather create 4 RAID-Z2 groups 
each made of 11 disks all of them in a single pool.

-- 
Robert Milkowski
http://milek.blogspot.com