Re: [PERFORM] What to do with 6 disks?
On Apr 19, 2005, at 11:07 PM, Josh Berkus wrote: RAID1 2 disks OS, pg_xlog RAID 1+0 4 disks pgdata This is my preferred setup, but I do it with 6 disks on RAID10 for data, and since I have craploads of disk space I set checkpoint segments to 256 (and checkpoint timeout to 5 minutes) Vivek Khera, Ph.D. +1-301-869-4449 x806 smime.p7s Description: S/MIME cryptographic signature
[PERFORM] What to do with 6 disks?
Now that we've hashed out which drives are quicker and more money equals faster... Let's say you had a server with 6 separate 15k RPM SCSI disks, what raid option would you use for a standalone postgres server? a) 3xRAID1 - 1 for data, 1 for xlog, 1 for os? b) 1xRAID1 for OS/xlog, 1xRAID5 for data c) 1xRAID10 for OS/xlong/data d) 1xRAID1 for OS, 1xRAID10 for data e) . I was initially leaning towards b, but after talking to Josh a bit, I suspect that with only 4 disks the raid5 might be a performance detriment vs 3 raid 1s or some sort of split raid10 setup. -- Jeff Frost, Owner [EMAIL PROTECTED] Frost Consulting, LLC http://www.frostconsultingllc.com/ Phone: 650-780-7908 FAX: 650-649-1954 ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Re: [PERFORM] What to do with 6 disks?
http://stats.distributed.net is setup with the OS, WAL, and temp on a RAID1 and the database on a RAID10. The drives are 200G SATA with a 3ware raid card. I don't think the controller has battery-backed cache, but I'm not sure. In any case, it's almost never disk-bound on the mirror; when it's disk-bound it's usually the RAID10. But this is a read-mostly database. If it was write-heavy, that might not be the case. Also, in general, I see very little disk activity from the OS itself, so I don't think there's a large disadvantage to having it on the same drives as part of your database. I would recommend different filesystems for each, though. (ie: not one giant / partition) On Tue, Apr 19, 2005 at 06:00:42PM -0700, Jeff Frost wrote: Now that we've hashed out which drives are quicker and more money equals faster... Let's say you had a server with 6 separate 15k RPM SCSI disks, what raid option would you use for a standalone postgres server? a) 3xRAID1 - 1 for data, 1 for xlog, 1 for os? b) 1xRAID1 for OS/xlog, 1xRAID5 for data c) 1xRAID10 for OS/xlong/data d) 1xRAID1 for OS, 1xRAID10 for data e) . I was initially leaning towards b, but after talking to Josh a bit, I suspect that with only 4 disks the raid5 might be a performance detriment vs 3 raid 1s or some sort of split raid10 setup. -- Jeff Frost, Owner [EMAIL PROTECTED] Frost Consulting, LLC http://www.frostconsultingllc.com/ Phone: 650-780-7908 FAX: 650-649-1954 ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq -- 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 7: don't forget to increase your free space map settings
Re: [PERFORM] What to do with 6 disks?
Jeff, Let's say you had a server with 6 separate 15k RPM SCSI disks, what raid option would you use for a standalone postgres server? a) 3xRAID1 - 1 for data, 1 for xlog, 1 for os? b) 1xRAID1 for OS/xlog, 1xRAID5 for data c) 1xRAID10 for OS/xlong/data d) 1xRAID1 for OS, 1xRAID10 for data e) . I was initially leaning towards b, but after talking to Josh a bit, I suspect that with only 4 disks the raid5 might be a performance detriment vs 3 raid 1s or some sort of split raid10 setup. Knowing that your installation is read-heavy, I'd recommend (d), with the WAL on the same disk as the OS, i.e. RAID1 2 disks OS, pg_xlog RAID 1+0 4 disks pgdata -- --Josh Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] What to do with 6 disks?
My experience: 1xRAID10 for postgres 1xRAID1 for OS + WAL Jeff Frost wrote: Now that we've hashed out which drives are quicker and more money equals faster... Let's say you had a server with 6 separate 15k RPM SCSI disks, what raid option would you use for a standalone postgres server? a) 3xRAID1 - 1 for data, 1 for xlog, 1 for os? b) 1xRAID1 for OS/xlog, 1xRAID5 for data c) 1xRAID10 for OS/xlong/data d) 1xRAID1 for OS, 1xRAID10 for data e) . I was initially leaning towards b, but after talking to Josh a bit, I suspect that with only 4 disks the raid5 might be a performance detriment vs 3 raid 1s or some sort of split raid10 setup. ---(end of broadcast)--- TIP 8: explain analyze is your friend
