We have 2 servers which have 6 SATA 7200 disks inside (each). We want to configure both servers so that they will have Window Server 2008 R2 Enterprise installed and on top of it Exchange 2010 x2 (for 300 people) as one virtual machine and AD x2 as another virtual machine and maybe some additional VM's (but not that much.
Now we are asking ourselves if it's better to create 3 RAID groups RAID 1 or (RAID 1 and RAID 10 scenario). We're looking for performance and protection. Of course SATA drives were choose because of costs and there's no real option to choose something else.
Idea 1:
- Raid A -> 2 x 1TB (RAID 1) -> C partition for system + D partition for Exchange logs
- Raid B -> 2 x 1TB (RAID 1) -> E partition - all virtual machines
- RAID C -> 2 x 1TB (RAID 1) -> F partition - exchange database
Idea 2:
- Raid A -> 2 x 1TB (RAID 1) -> C system partition + exchange logs
- Raid B -> 4 x 1TB (RAID 10) -> all virtual machines, exchange db
Idea 3:
- Raid A -> 6 x 1TB (RAID10) -> system, all vm's, exchange db, exchange logs
Idea 4:
- ?
Which of the option is the best? Will having RAID 10 on 4 drives mitigate the problem of putting multiple stuff on one big drive so access speed may be slower if all things at once hit the same target?
Just use one bit 6-way RAID10 array per server, it's kind of pointless doing anything else as you're using such slow drives and you'll lose some IO performance due to virtualisation anyway (you didn't mention hypervisor or disk access method by the way).
I would definitely go for a one single RAID 10. Multiple RAIDs, separate for database/system/whatever are 90s thinking. In the age of LVMs and virtual disks, resizeable partitions, etc., this is obsolete and greatly impacts performance. And there is no real benefit. (I am answering this question despite the fact, that a lot of folks have already done the same just to emphasize the right answer. Utilize all the bandwidth and go for one big array).