(Sorry posted this first in storage then realised this is probably the better place)
We're looking to upgrade the drives in our file server (lots of small random stuff going on) and I'm torn between the new Velociraptors and 15k SAS. From what I can make out on storagereview.com, 15k SAS would still be better by a significant margin. Having said that I've seen an access time of 3ms for the current Velociraptor which seems pretty good. Wondering if anyone has any thoughts? thanks
The answer might depend on your budget. If you have lots of random reads/writes and performance beats price, I would recommend SSDs. An array of SSDs would absolutely trump any spinning disk when it comes to random read/write. For SMBs, I would look at drives with good endurance levels like the Intel DC 3500/3700, the Micron M500DC, or even Seagate 600 Pro. Even the Samsung 840 Pro is usable, especially when you use the larger capacities and over-provision (or under-partition) the drive.
Second, if SSDs aren't a viable solution for you, I would take 15k SAS over 10k Velociraptor. When you stick Velociraptor drives in an array, any small gain in access times might not be seen when all of the drives are being queried by the RAID controller. A good RAID controller might actually speed your access up more so than any small differences between 15 SAS drives and 10k 'raptors. Finally, when you get to the file itself, the 15K SAS drives will have a larger overall transfer rate than the 10k drives.
When you stick Velociraptor drives in an array, any small gain in access times might not be seen when all of the drives are being queried by the RAID controller.
Thanks - why do you say that? We're actually using software RAID 1 which has support for striped reads.
Well, with two drives, RAID-1 is actually mirroring - it's not striping (RAID-0). A dedicated RAID controller can make more intelligent decisions about the data requests coming in (such as using its cache to fulfill a request or such as re-ordering requests) as well as process the RAID parity logic faster. In a small two-drive setup, it won't make as much of a difference; in larger multi-drive arrays, a good RAID controller does better.
If you're using two drives & can't afford much, then I would recommend switching to two SSDs in RAID-1 (mirrored). You see a huge difference using 512GB/1TB SSD drives over two spinning disks.
Edit: 256GB SSDs would work as well, although I imagine you would want more capacity if you're "upgrading" space.