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What rule do you follow when buying disks for RAID arrays:

  • to buy the disk as similar as possible?
  • to buy the disks from different manufacturers?

Some people chose the same type for performance and compatibility reasons. Some chose different manufacturers to lower the chances for 2 disk to fail at the same time.

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up vote 1 down vote accepted

It is familiar subject but I do not think it matured into some kind of rule yet. My approach is to use drives from same manufacturer but not from the same batch. At the moment, we mostly use 2TB WD drives and we maintain a spare pool of 3-6 drives. Every time we need to add storage we buy another set of drives and then we use all drives from the pool with the rest of drives from the new arrival.

I was considering using drives from different vendors also, but it felt kind of too risky. If you look at number of sectors in 2TB drive from Seagate and WD for instance they are not the same. It is not to hard to work around this difference, but it just one extra thing that may go wrong and this was the main reason why we decided against it. Also, we get better price from our vendor if we buy all drives of the same manufacturer.

I have to note that we use RAID-6 on most of our storage arrays and importance two disk failure is rather low so I'm not too religious about this practice.

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