Anyone running 4x SSD in RAID 0?

Shad · 16 Aug 2012 at 08:03

I'm looking at running 4x ~256Gb SSDs in a RAID 0 array but just curious if anyone else has done this and what kind of numbers you get. I'll be limited to SATA2 speeds using a PERC 6 controller but since that should give in excess of 250Mb/s sequential read for a single drive, am I being overly optimistic to expect around 800Mb/s read for 4 drives?

What I do know so far is that on my AMD workstation I run a pair of 500Gb mechanical drives in RAID 0 and get 200Mb/s read/write and on the server at the moment there are 4x 250Gb mechanical drives in RAID 0 (3 are the same, one isn't, all quite old) and that gets about 230Mb/s read/write, but using a more basic SAS 6 card. I would expect that 4 decent modern mechanical drives of that capacity would see 350-400Mb/s - right? Or about half the performance of the SSDs, in theory.

Unless I'm way off with this

Shad · 16 Aug 2012 at 08:58

Completely understand, I just fitted an SSD in my netbook and it went from barely usable to almost as fast as my workstation.

The purpose of this exercise is to make the maximum use of a 10Gb network link, which is primarily going to be used for video editing (storing source footage and cache files).

Does my rough math stack up? I'm guesstimating 3-3.5x the performance of one SSD, which seems reasonable based on what I've learned from RAID 0 so far.

Shad · 16 Aug 2012 at 09:17

It's PCI-e, x8. Good for 3.0Gb/s I believe, but the LSI SAS1078 chip wasn't designed with SSD in mind so it won't be completely optimal. But it should still be much faster than mechanical drives as long as I get the caching options right.

Shad · 16 Aug 2012 at 09:31

Yeah that's been a concern in the back of my mind. I believe some drives have their own built-in GC that works independently of the controller/OS, the Crucial M4s possibly?

All the data will be backed up so it's definitely an option to periodically zero out the drives

When I've got the kit together I'll also test out RAID 5 since that ought to make drive cleaning a bit simpler, removing the need to restore from backup (although doing that is of course a good test of the backup!).

Yup will be running 2008R2 but I can always create a 1024/2048mb partition manually. Thinking about it though... if blocks are going to be spread around the disks is it such a big deal on an array?