Andrew Kolakowski wrote:Really?
How long does 8x8TB RAID 5 rebuild? Day, 2, 3?
You have to be very unlucky to have 2nd failure before raid is rebuild.
Rebuild time depends on how much the controller can dedicate to it, but it will be painfully slow (days) compared to RAID 10. Restoring from backup could be faster even, depending on your infrastructure.
The point is that no, you do not need to be unlucky to encounter a second failure with 10^14 disks before the array rebuilds. Quite the opposite: with these disks, it is almost a statistical certainty. The second disk will not totally die like the first may have, but you will almost inevitably have at least one error, and that means lost data, period. Whether or not that data is valuable is up to chance. Just another reason we say RAID is not a backup.