>> Instead, how about a 6-drive RAID 10 array with no hot spare? My >> guess is this would mean much greater fault-tolerance both overall and >> during the rebuild process (once a new drive is swapped in). That >> would mean not only potentially increased uptime but decreased >> monitoring responsibility. > > RAID10 with six drives can be implemented one of two ways, > > Type 1: A B A B A B > > Type 2: A B C A B C > > If your controller can do Type 1, then going with six drives gives you > better fault tolerance than four with a hot spare. > > I've only ever seen Type 2, so I would bet that's what your controller > will do. It's easy to check: set up RAID10 with four drives, then with > six. Did the drive get bigger? If so, it's Type 2. > > If it's Type 2, then four drives with a spare is equally tolerant. > Slightly better, even, if you take into account the reduced probability > of 2/5 of the drives failing compared to 2/6.
Thank you very much for this info. I had no idea. Is there another label for these RAID types besides "Type 1" and "Type 2"? I can't find reference to those designations via Google. - Grant
