On Jul 18, 2007, at 4:27 PM, Alex Samad wrote:
I don;t have to worry about dying controller cards and incompatibilities and I am in the early stages of growing my raid5 from 200G drives to 500G drives live
Just as a point of interest, my experience with 3ware cards is that compatibility is not an issue with RAID 1 mirrors -- you can plug a drive from a RAID 1 mirror into an ordinary SATA controller and read it.
This is emphatically *not* true for RAID 5. In fact, a drive set up as a RAID 5 array member with a 3ware 9000-series controller won't even be recognized as a valid device by an ordinary SATA controller -- unless you connect it back to the RAID 5 controller and explicitly remove it from the array. This had me scratching my head a couple weeks ago. I decommissioned a 3ware 9500S RAID 5 array and then tried to re-use the drives elsewhere, and they just wouldn't work. I almost decided they'd gone bad somehow. A 3ware 8006 RAID 1 controller would recognize them as an incomplete array but was unable to do anything with them. Eventually it dawned on me to plug them back into the RAID 5 controller and delete the array, and after that they were fine. I don't know what the RAID 5 controller does with those drives but it's fairly evil. The performance boost and hot- swap capability are a nice benefit compared to software RAID, though.
David Brodbeck Information Technology Specialist 3 Computational Linguistics University of Washington
