2 disks died at once :(

carpii wrote:
BaJohn wrote: Technically, switching on the drives is a stressor event, and they were both switched on together (I assume). I normally try to use identical disks but from different batches in my NAS, but looking at the serial numbers it looks like they all came from the same batch, so maybe thats a factor too

That is one of the things that worries me 'long term', since I bought 7 disks together (6 + spare, see http://www.readynas.com/forum/viewtopic.php?f=24&t=80614) and obviously the 'end of life' will occur at a similar time. I am not certain that different batches of the same disk would make significant difference. Anyway it would mean buying from (worst or is that best, case) 7 different suppliers.
I almost wish I have a 'farm' of NAS systems so I could rotate them. :idea:

One other thought - maybe at start up there is a lot of vibration in your system. Maybe they ALL fire up together, or are they sequentially, either of which could be a problem if the mounting is not good. Possible some resonance occurred in the supporting desk/rack etc.