That's why serious SAN vendors take care to provide you a mix of disks (e.g. on a brand new NetApp you can see that disks are of 2-3 different types, and with q

That's why serious SAN vendors take care to provide you a mix of disks (e.g. on a brand new NetApp you can see that disks are of 2-3 different types, and with quite different serial numbers).