RAID 5 drive replacement schedule

["Murda Mcloud" <murdamcloud () bigpond com>]

In my mind, this a security related question as it has to do with ensuring
availability.

Does anyone have links towards any whitepapers etc that suggest replacement
of disks in a RAID 5 array as part of a maintenance cycle?

If all the drives in an array are the same age and one fails; does this mean
the others are more likely to fail. I'd imagine so as they have had the same
amount of usage.