I understand about the different types of RAID configurations:
- RAID 1 -- Mirror [Redundant]
- RAID 0 -- Stripe [Performant]
- RAID 5 -- Hot Spare [Redundant]
From what I understand, RAID 1 gives you redundancy with no performance hit, RAID 0 gives you performance at the cost of redundancy, and RAID 5 is good in the senes that you gain extra storage space and still have redundancy, at the expence of performance.
I also understand a bit about Nested RAID configurations, specifically RAID 10 (1+0). This provides the benifit of both RAID 1 + RAID 0. Giving you the best of both worlds.
My question is this: (And a SAN is out of the question here) Would a RAID 50 or a RAID 10 be better suited for a virtualization environment where most VMs are very under used in terms of disk IO and CPU use. I'm trying to maximize the number of VMs I can put on a host machine, and my limiting factor is drive space.
So, I'm trying to put as many VMs on a Virtual Host as possible, most of the IO on any of the VMs will be OS related and on occasion user requests will trigger a VM to do some IO, but this is rare and relativly evenly distributed across VMs.
My thought is that the RAID 50 could prove better because A) better use (2/3 total size of all disks in the array instead of 1/2) and B) potentially better better random read/write performance since there are more drives in play for storage, so read/write seeks are more likely to be on different physical drives.
Virtual Hosts - Windows Server 2008 R2
Virtual Machine - Windows 2000 Server - Windows Server 2008 R2
Single hardware RAID controller. Which I assume would do parity calculations?
Two RAID 5 arrays < 10 total drives
Raw performance is not an issue in most situations, the main limiting factor is physical drive space. Most of the IO is just OS chatter. Due to limitations in our database software we need a 1-server::1-system, even if its only 5 users. So most of our database servers sit idle. The overhead is just running that many OSes on the drive array.
I am currently using a RAID 10, and it is working just fine; but I'm finding that more drive space would be useful, (thus the inquiry about RAID 50 for better use of physical disks). As suggested below, I'm hearing that RAID 6 could offer similar performance, redundancy, and storage capacity as RAID 50 -- is that true or am I not understanding the responses?