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 Failures
This 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.
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