Re: Looking for a cheap upgrade (RAID) - Mailing list pgsql-performance

From Josh Berkus
Subject Re: Looking for a cheap upgrade (RAID)
Date
Msg-id 200305021510.25982.josh@agliodbs.com
Whole thread Raw
In response to Re: Looking for a cheap upgrade (RAID)  ("scott.marlowe" <scott.marlowe@ihs.com>)
Responses Re: Looking for a cheap upgrade (RAID)
List pgsql-performance
Scott,

> With that setup, you'd have 15 Gigs for the OS, 4 gigs for swap, and about
> 300 gigs for the database.  The nice thing about RAID 5 is that random
> read performance for parallel load gets better as you add drives.  Write
> performance gets a little better with more drives since it's likely that
> the drives you're writing to aren't the same ones being read.

Yeah, but I've found with relatively few drives (such as the minimum of 3)
that RAID 5 performance is considerably worse for writes than RAID 1 -- as
bad as 30-40% of the speed of a raw SCSI disk.   This problem goes away with
more disks, of course.

--
-Josh Berkus

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