Rob,
You have NO choice but to add them as a second parity set from what
you describe. If you have 4328 disks in the parity set, you can't add 4327
disks to the same raid set. All disks in a raid set need to be the same
size.
Also, I prefer multiple raid sets which will require more space for
the parity, but decreases the odds of losing 2 disks in one raid set. You
have less disks in each set, with more sets.
Pete
Pete Massiello
iTech Solutions
http://www.itechsol.com
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-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Monday, February 15, 2010 9:19 AM
To: Midrange Systems Technical Discussion
Subject: Is there a performance advantage of adding a second parity set?
We have a system with 17 drives. We are going to add six 70GB drives. If
I add them two at a time they will add them to the existing parity set. If
I add them all at once it will start a new parity set. Starting a new
parity set effectively ties up one of the 70GB drives to raid striping. We
really don't need the space though - we just have 70GB drives laying
around. Without the new drives we are only at 50% used. The existing
parity set has the striping across 8 drives. I take it the new set would
have the striping across 4 drives?
These six 4327's would go into a 5787. Into P1-D1 through P1-D6.
P1-D7 through P1-D12 are 4328's. P2-D1 through P2-D5 and P2-D7 through
P2-D11 are 4328's. Leaving P2-D6 and P2-D12 open.
Rob Berendt
midrange.com
