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> a simultaneous 2 disk failure in a storage array (...) is a very unusual event I'd disagree. If you have same model, same production batch of harddrives in a
by dexen 15y ago
> a simultaneous 2 disk failure in a storage array (...) is a very unusual event
I'd disagree. If you have same model, same production batch of harddrives in a RAID, the chances of simultaneous failure is elevated. Depending on RAID level and workload, it's quite possible two or more drives are loaded (accessed) in exactly the same way. If, again, they are from the same production batch, chances are they have similar production defects in mechanics or semiconductors, thus it makes sense they'd fail almost simultaneously.
- dh 15y agoThe drives in this array are mixed and from different production batches and some have been replaced at different times for a number of reasons. Across an array this size 2 disks failing at the exact same time is very rare as verified by the vendor.
- btucker 15y agoThe production batch issue is very real. After seeing an 85% failure rate over 12 months in a batch of 16 high-end Seagates, we no longer purchase more than a few at a time from a particular vendor. Though I will say, even with this, we never had a simultaneous failure.
- gtuhl 15y agoAgreed, hard drives fail constantly. I've had as many as 3 dead at a time while waiting for hot spares to rebuild in arrays as small as 24 drives. Dual drive failures have happened at least twice that I can remember off the top of my head in the last 3-4 years. Usually running raid10 for performance reasons but when I don't need fast writes I use raid6 instead of raid5 for anything beyond 8 drives.