>> http://blog.open-e.com/why-a-hot-spare-hard-disk-is-a-bad-idea/ >> >> "Based on our long years of experience we have learned that during a >> RAID rebuild the probability of an additional drive failure is quite >> high – a rebuild is stressful on the existing drives." > > This is NOT true on a RAID 10... a rebuild is only stressful on the other > drive in the mirrored pair, not the other drives. > > But, it is true for that one drive.
Why wouldn't it be true of RAID 10? Each drive only has one mirror, so if a drive fails, its only mirror will be stressed by the rebuild won't it? > That said, it would be nice is the auto rebuild could be scripted such that > a backup could be triggered and the auto-rebuild queued until the backup was > complete. > > But, here is the problem there... a backup will stress the drive almost as > much as the rebuild, because all the rebuild does is read/copy the contents > of the one drive to the other one (ie, it re-mirrors). > >> 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. > > I would still prefer a hot spare to not... in the real world, it has saved > me exactly 3 out of 3 times... You would prefer 4-drive RAID 10 plus a hot spare to 6-drive RAID 10? Isn't 6-drive RAID 10 superior in every way except for cost (1 extra drive)? - Grant
