S Glasoe wrote:
I want the array to be able to survive a two disk failure, so RAID6 would be the obvious choice, but ...
Depends. Is the data read or write intensive? What performance parameters are you trying to achieve?
Data is generally write intensive, but reliability is more important than performance. I understand that RAID6 is slow(er) for writes.
What budget are you trying to meet? RAID5/6 is slow on writes. RAID10 (RAID0 + RAID 1) with hot spares would be my idea of surviving multiple drive failures at any time and maintaining decent performance for reads and writes.
But can a RAID10 setup take a two drive failure?
Will these controllers be able to talk to each other in a redundant fashion? At the hardware/firmware/driver level?
At the hardware level - the redundancy is transparent to the host-system.
Give us more info about the specific hardware and the 'application' you are trying to support.
This is an HP/Compaq Storageworks array, connected over FC-AL to two servers. The application is primarily email-storage, probably divided into 90% write, 10% reads.
I look to eliminate complexity from a system like this. What is the easiest way to monitor, replace and rebuild the hardware/drives and data you are trying to protect?
The array controllers take care of all that, except the monitoring.
Redundant controllers are nice but if you can't hot-swap a failed one in a running machine can the 'application' afford the downtime to do a replace and rebuild?
A controller can also be hot-swapped - AFAIK. I'd have to double-check, but I'm pretty certain. Any reason why you haven't discussed RAID6 at all? I haven't looked at it much myself, but it sounds like a pretty good option. /Per Jessen, Zürich