> Personally, I never touch raid5, but then, I'm on sata. I do agree > that there are benifits to hardware raid with battery backed cache if > you do use raid5 (but I think raid5 is usually a mistake, unless it's > all read only, in which case you are better off using main memory for > cache. you are trading away small write performance to get space; with > disk, space is cheap and performance is expensive, so personally, if > I'm going to trade I will trade in the other direction.) > > Interesting thoughts on raid5 although I doubt many would agree. I don't see how the drive type has ANYTHING to do with the RAID level. There are different RAID levels for different situations I guess but a RAID 10 (or 0+1) will never reach the write or read performance<http://www.tomshardware.com/reviews/external-raid-storage,1922-9.html>of a RAID-5. The disk space waste isn't too much of a problem anymore because as you say drives are getting much cheaper. Although on that subject I'll mention that enterprise drives and desktop drives are NOT the same thing. We deal in hundreds of drives and see about a 3% failure on desktop drives and only a fraction of that on enterprise drives. I will say though that in my opinion the one really important thing to consider is the price. These controllers aren't cheap and if you skimp you will pay. For sequential single reads (streaming one stream) I'd consider using a software "RAID" 0. For a mirror I'd consider Software RAID but once I get serious and go for RAID5 or RAID6 I'd only use Hardware RAID. That's my 2 cents. :-) Grant McWilliams -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos-virt/attachments/20091202/c1d5d66c/attachment-0004.html>