On Thu, Sep 16, 2004 at 02:07:37PM -0700, Josh Berkus wrote: > Jim, > > > What about benefits from putting WAL and pg_temp on seperate drives? > > Specifically, we have a box with 8 drives, 2 in a mirror with the OS and > > WAL and pg_temp; the rest in a raid10 with the database on it. Do you > > think it would have been better to make one big raid10? What if it was > > raid5? And what if it was only 6 drives total? > > OSDL's finding was that even with a large RAID array, it still benefits you to > have WAL on a seperate disk resource ... substantially, like 10% total > performance. However, your setup doesn't get the full possible benefit, > since WAL is sharing the array with other resources. Yes, but if a 3 drive raid array is 40% slower than a single disk it seems like the 10% benefit for having WAL on a seperate drive would still be a losing proposition.
BTW, my experience with our setup is that the raid10 is almost always the IO bottleneck, and not the mirror with everything else on it. -- Jim C. Nasby, Database Consultant [EMAIL PROTECTED] Give your computer some brain candy! www.distributed.net Team #1828 Windows: "Where do you want to go today?" Linux: "Where do you want to go tomorrow?" FreeBSD: "Are you guys coming, or what?" ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
