On Thu, Aug 5, 2010 at 5:13 PM, Dave Crooke <dcro...@gmail.com> wrote: > Definitely switch to RAID-10 .... it's not merely that it's a fair bit > faster on normal operations (less seek contention), it's **WAY** faster than > any parity based RAID (RAID-2 through RAID-6) in degraded mode when you lose > a disk and have to rebuild it. This is something many people don't test for, > and then get bitten badly when they lose a drive under production loads.
Had a friend with a 600G x 5 disk RAID-5 and one drive died. It took nearly 48 hours to rebuild the array. > Use higher capacity drives if necessary to make your data fit in the number > of spindles your controller supports ... the difference in cost is modest > compared to an overall setup, especially with SATA. Make sure you still > leave at least one hot spare! Yeah, a lot of chassis hold an even number of drives, and I wind up with 2 hot spares because of it. > Parity RAID simply isn't suitable for database use .... anyone who claims > otherwise either (a) doesn't understand the failure modes of RAID, or (b) is > running in a situation where performance simply doesn't matter. The only time it's acceptable is when you're running something like low write volume report generation / batch processing, where you're mostly sequentially reading and writing 100s of gigabytes at a time in one or maybe two threads. -- To understand recursion, one must first understand recursion. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
