On Mon, Nov 21, 2005 at 10:34:36AM +0100, Mario Splivalo wrote: > > RAID5 generally doesn't make for a fast database. The problem is that > > there is a huge amount of overhead everytime you go to write something > > out to a RAID5 array. With careful tuning of the background writer you > > might be able to avoid some of that penalty, though your read > > performance will likely still be affected by the write overhead. > > RAID5 was not ment to improve performance, but to minimize disaster and > downtime when your hard disk dies. We're using RAID5 with postgres. In > the last 3 years we changed 5 disks, but the system downtime was zero > minutes. And the same would have been true with RAID10. In fact, RAID10 is more reliable than RAID5; depending on what drives fail it's possible to lose up to half of a RAID10 array without any data loss. If you ever lose more than 2 drives at once with RAID5, your data is gone. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
