On Wednesday 28 May 2008 1:47:32 pm Josh Paetzel wrote: > On Wednesday 28 May 2008 11:14:50 am Justin Krejci wrote: > > http://download.intel.com/support/motherboards/server/srcsas18e/sb/axxrpc > >m2 _ tps_10.pdf > > > > Benefits are identified in this PDF. > > Data caching (write-back cache can greatly improve write performance) > > > > Busy databases servers commonly need lots of I/O > > > > Also consider running RAID10 if you have drive availability (4 drive > > minimum) as you will get much higher I/O performance with that as well > > especially with writes. Though if you need the capacity, RAID5 will give > > you one drive more of capacity. RAID10 can also give you a smaller chance > > of data loss due to drive failures as you can potentially lose up to half > > of your drives and still operate whereas using RAID5 and losing 2+ drives > > = disaster. > > Somewhere a DBA just rolled over in his grave at the mention of a database > using RAID 5. If you're ever going to care about performance at all don't > use RAID 5. It's particularly slow at the sorts of write I/O database > systems typically generate. For the most part this is true, however on a lot of modern RAID controllers if you hook 12 drives up in RAID-5 you are going to see amazing performance. Here is an article with a very thorough review of 9 SATA RAID cards: http://tweakers.net/reviews/557/26/comparison-of-nine-serial-ata-raid-5-adapters-pagina-25.html The issue here is that they do not do a RAID-10 test with 12 drives. I don't know what they are doing on the Coraid SR 1521 to make RAID-5 faster than RAID-10, but when you get up to 14 drives in the chassis you get much better throughput, now mind you this is not random I/O, just another thing to think about: http://coraid.com/support/sr/ANSR002.pdf For a large number of drives in a RAID-5 you get really good performance and much higher capacity. Not that this is really relevant to the original poster. Thanks. -- Bret Baptist Senior Network Administrator bbaptist at iexposure.com Internet Exposure, Inc. http://www.iexposure.com (612)676-1946 x17 Providing Internet Services since 1995 Web Development ~ Search Engine Marketing ~ Web Analytics Network Security ~ On Demand Tech Support ~ E-Mail Marketing ------------------------------------------