Never RAID 5 for a database. When I say "never," I can give you edge-case 
scenarios, but you're basically taking a 4x overhead on all writes. Now, RAID-0 
is a bad choice as well, since JBOD has no replication, but it sounds like you 
might have that end under control.

-------- Original message --------
From: Rene Romero Benavides <rene.romer...@gmail.com> 
Date: 08/27/2013  5:35 PM  (GMT-06:00) 
To: pgsql-admin@postgresql.org 
Subject: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 
(self replicating SAN) 
 
Thanks for your attention.
What would you choose for a postgresql installation: 3 disks configured with 
RAID 0 (in a self replicating SAN) over 10 disks configured with RAID 5 (also 
in a self replicating SAN) , we have space constraints that prohibit us from 
choosing RAID 1+0.
I've been persuaded to choose RAID 5, because writes and parity computation 
will be spread over 10 disks compensating write overhead providing a better 
level of data security. 

Do you think it was a good decision? Any comment will be appreciated. Have a 
good day.

-- 
El genio es 1% inspiración y 99% transpiración.
Thomas Alva Edison
http://pglearn.blogspot.mx/

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