The best of all worlds is to use a HW RAID card with battery backed cache.
Then you can have both high performance and high reliability.
Benches suggest that the best such cards currently are the Areca cards which support up to 2GB of battery backed cache.
Ron
-----Original Message-----
>From: Mark Lewis <mark.lewis@mir3.com>
>Sent: Apr 28, 2006 1:47 PM
>To: Vivek Khera <vivek@khera.org>
>Cc: Pgsql performance <pgsql-performance@postgresql.org>
>Subject: Re: [PERFORM] hardare config question
>
>It's also possible that the single SATA drive you were testing (or the
>controller it was attached to) is lying about fsync and performing write
>caching behind your back, whereas your new controller and drives are
>not.
>
>You'll find a lot more info on the archives of this list about it, but
>basically if your application is committing a whole lot of small
>transactions, then it will run fast (but not safely) on a drive which
>lies about fsync, but slower on a better disk subsystem which doesn't
>lie about fsync.
>
>Try running a test with fsync=off with your new equipment and if it
>suddenly starts running faster, then you know that's the problem.
>You'll either have a choice of losing all of your data the next time the
>system shuts down uncleanly but being fast, or of running slow, or of
>fixing the applications to use chunkier transactions.