Everyone makes that mistake once. It is an understated problem in building fault tolerant storage arrays.
We buy a batch of 20 drives all at the same time, and they are all the same manufacturer, model, size etc... Possibly even from the same batch or date of manufacture. Then we put them in continuous use in the same room, at the same temperature, in the same chassis. Finally they have an almost identical amount of reads/writes.
Then we act shocked that two drives fail within a short interval of each other :)
Just a couple of weeks ago, I upgraded my home storage system from 9 disks (4x3 raidz) from the same manufacturer with partially consecutive serials.
Now its 18 disks (3x6 raidz2) from 3 different manufacturers and every vdev has 2 of each. And the vdevs are physically evenly spread throughout the case.
I sleep so much better. It was kind of a miracle the first setup survived the 4.5 years it did.
We buy a batch of 20 drives all at the same time, and they are all the same manufacturer, model, size etc... Possibly even from the same batch or date of manufacture. Then we put them in continuous use in the same room, at the same temperature, in the same chassis. Finally they have an almost identical amount of reads/writes.
Then we act shocked that two drives fail within a short interval of each other :)