On 3/10/2011 12:19 PM, John R Pierce wrote:
That controller doesn't really support RAID, what you're getting is commonly called FakeRAID
If you are referring to the 1068E, that is completely wrong.
They do have basic hardware raid, with an embedded control processor, but they don't have any battery back write-back cache, which negates any real advantages of hardware raid.
How important is the card-level battery if you have a UPS and a scheme to monitor it and do a graceful shutdown before it fails?
I always configure those as simple SAS controllers and use the OS native software raid (mdraid mirroring in the case of Linux). I also almost never use any raid level above raid1 or 10 (mirror or stripe/mirror).
I like raid 1 myself because you can recover data from any remaining disk after a failure and software raid because you can use any vendor's controller for that recovery, but if you use raid 5 you might want the hardware controller to do the parity computation work.