I agree on the brand you can trust and the CMR, but dont agree on multiple versions.
However, drives with the same MTBF are mathematically more likely to fail than those with staggered MTBFs. So that suggests over time, staggering the age of drives used can have some advantage in reducing the likelihood of multiple simultaneous failures versus all used from a single batch at the same time.
If you have a 5 drive raid and lets say they are identical made drives, you have a much higher chance of more than 1 of the drives deciding to fail at the exact same time. And for a 1 drive fault tolerant raid that would be bad.
Where as if all the drives are from different lots, the odds of them having an identical defect go down. Ergo, the odds of more than 1 failure at the same time go down.
Here is a real world example (and I had something similar):
Yesterday I had two drives in one of our storage arrays fail within 10 minutes of each other. It was fine in the end - fortunately there were no issues during the rebuild, and we have plenty of backups anyway - but I still feel slightly rattled by it. Has anyone had this happen before? The...
community.spiceworks.com
Sample Size: 37 Clients, each of them has 1x ST4000DX001-1CE168 plus 1x HDS721010DLE630 or HDS721680PLA380 or ST380815AS - plus 5x ST4000DX001-1CE168 in servers. Hitachi HDS721010DLE630 05ReallocatedSectors 027 Hitachi HDS721010DLE630 05ReallocatedSectors 022 Hitachi...
www.truenas.com
I've had a little look around and not found any clear answer about this. Is it generally considered a good idea to purchase your drives in groups from different sellers? I plan on buying 8x4tb drives to run in raidz2, should I look to buy 4 drives from one seller and then the other 4 from...
www.truenas.com
I'm not saying there is a right or wrong here, just having nearly lost a LOT of data due to a simultaneous failure of multiple identical drives from a single batch, I have vowed never to do that again. From one of the posts I linked to above:
I had a near data death experience just like the one above where one drive outright died and another from the batch lasted barely long enough for me to copy off the data before it died permanently. I'm talking within hours of one another. And if they both died, that's it, all data would have been POOF.
Having drives from different batches, I have never again suffered a simultanous multi drive failure again. I dont even care if the drives die within the same week/month. But just some reasonable separation in time from minutes/hours apart, where you can slap in a replacement drive to rebuild the RAID.
That said, perhaps I havent had the simultaneous failure had nothing to do with different batches of drives and was just good luck, and perhaps my multi drive failure on the same batch of drives was simple bad luck.
I'm not telling you to change your preference. Just one more variable to consider. Everyone's use cases differ. And having drives match can have other benefits that you may care about more than I do the failure risk. No wrong or right answers, just depends on your use case.