VMWare - Raid 10 on 10k SAS v Raid 1 on 15k SAS

Max Powers · 15 Dec 2011 at 11:27

I have a decision to make for a fairly high IOPs database, which I am going to Virtualise.

At the moment the DB sits on our Dell SAN, using a 4 disk Raid 10 config, on 10K SAS drives.

This gives me more disk space than we need for the database, but a good level of redundancy.

I also have available, 3 15k SAS drives, which are larger in size. These could be configured in a RAID 1 array, with the 3rd disk marked as a hot spare.

My question is: would you see better performance in the RAID 10 on slower drives, or the RAID 1 on faster drives?

Thanks for your views!

MikeHiow · 15 Dec 2011 at 11:43

As RAID10 is striping, and the 10K drives aren't half the speed, I'm fairly confident you'll find better performance on the RAID10 setup assuming there are no other contributing factors.

However, if you've got other stuff on the same drives on your SAN, then I think I'd rather opt for the dedicated RAID 1 setup.

Can you not find another 15K drive and go RAID10 on that?

Shaz]sigh[ · 15 Dec 2011 at 11:53

What sort of IOPS? What read/write ratio? Is it VMFS or RDM? Is it sequential or random? Are the disks standalone or shared?

Stolly · 15 Dec 2011 at 16:20

that amount of spindles isn't going to give you a lot of IOPS in any case.....

kerrgreg · 22 Dec 2011 at 10:29

Raid one is slow to write, raid 10 is much faster to write and read times are faster too. Raid 10 will be faster even with the difference of the drives