Fri Mar 05, 2010 8:56 pm
OK - I'm going to chuck my opinions in here. I could be wildy off the mark so feel free to ignore them!
1) If you are thinking about using motherboard raid (e.g. Intel Matrix RAID) then don't. Especially if you need to parity RAID (5 and 6). Ideally, get a proper RAID card with onboard battery backed cache, failing that get something with adecent SAS RAID controller built in (e.g. Supermicro with onboard LSI RAID).
2) Don't use consumer disks unless they've been verified with the RAID controller, and even then be wary. Make sure you get the RAID edition drives, as desktop drives tend to have firmware which doesn't work well in RAID. For instance, many drives will halt data transfer if they encounter an error and will attempt to correct it. If they take too long to do this and they are on a RAID controller, the controller may drop the drive from the array.
3) Don't get velociraptors. I agree with Anton, the original Raptors work well in RAID (I once ran Exchange 2003 for 100+ users off 4x 74GB Raptors), but be very wary of the newer Velociraptors. I got hit by the 45 day bug in the firmware... However the 2TB RE4 has been fine for me.
4) Are you building this server yourelf? In that case, get cold spare drives rather than relying on the drive manufacturers warranty. You cannot rely on the RMA process to be speedy. If you are going HP/Dell/IBM then get an onsite warranty.
5) Exchange loves IOPS more than transfer rates. Things may have changed with 2010 (I'm not familiar with it) but for 2000-2003-2007 you were best off with multiple exchange dbs on mutliple RAID volumes. That way if you have a drive failure, the peformance hit only affects some of your users, and total IOPs is increased.
6) Consider SAS drives. They aren't that much of a premium (e.g. Seagate Savvio 10K.3 - £230 vs WD Velociraptor @ £170). SAS has better error correction than SATA, and sometimes better performance, as it's full duplex.
7) Consider your rebuild time. A 300GB RAID-1, on 10K disks, will rebuild in two hours. A 2TB RAID-1 could be over five hours at 100MB/sec. I would go for more, smaller disks for Exchange, and fewer, bigger disks for your files.
If your CPU isn't involved in the RAID (i.e. you have a hardware raid controller) then a single 55xx series CPU should be fine unless you are going to be saturating multiple 10GBit NICS. Get a dual socket motherboard, but only but a second CPU if you really need to. Starwind itself is very efficient - I can get to 500MB/sec over 10GbE before I saturate CPU - but that's with Starwind 4.2 running in a hyper-v vm with only one cpu core assigned to it.
cheers,
Aitor