Question:
??????
??Want to improve this question? Update the question so it’s on-topic for Super User. ?
??
Closed 7 years ago.
???? ??Improve this question ?? ?
We often see advice about mixing hard-drive’s model or brand for RAID arrays (also works for any disks groups, for example a ZFS pool).The rationale is: drives produced in the same batch tend to have same intrinsic problems, so tend to fail together.
I use identical drives for RAID since years on 60+ systems. I never noticed any problem.But other people do.Point of view, statistics, coincidence, luck, fate… or real hazard ?
Is there any (serious) study or source about drive pairing in a RAID ?
The only good argument I know until now is about firmwares: when a drive bricks because of a firmware bug, the twin is very likely to fails in a narrow time frame. But also a similar drive from another batch. This is a rare event, but we speak about small improvements between two methods, so rare events count in the balance.
Answer: I know 2 papers about hard-drives and/or RAID:
Using Device Diversity to Protect Data against Batch-Correlated Disk FailuresThis one is based on a batch failure, but no discussion about the frequency of such problem.
Disk failures in the real world: What does an MTTF of 1,000,000 hours mean to you?This one is based on a study against 100,000 disks, and there a little coverage about batches.