Ken Schneider wrote:
Search around some more for an array controller that provides raid 6, it is the only way you will get "two drive failure" and make sure -all- of the drives are hot swappable. Employ alert notification using SNMP for when a drive fails and have spares on hand at all times.
Changing the controller is not an option - and although the firmware is upgradeable and patchable, I don't think HP is likely to add RAID6 at this time. All the drives are hot-swappable, and the array will automatically use hot spares. Herman Knief wrote:
Actually, if you setup RAID 10 correctly (striped mirror sets) then you can have half of your drives fail, so long as you don't have two in the same mirror set go at once.
Exactly. It's that bit of "so long as" I don't like :-)
Going with RAID 5 or 6 incurrs a write perofrmance penalty which may or may not be tolerated by the app. This can be overcome by a good amount of battery backed cache on the front end though. Essentially, you have performance, reliability, cost as concerns: pick any two and those will drive your decisions.
Reliability & cost are the two main criteria right now - and in that order. /Per Jessen, Zürich