Match harddrives in a RAID 3?

[BrianS]

If I have a RAID 3 array at work, do all the drives need to be the same drive? same size? Is it "Best Practice" to have them all be the same or any other reason you need to have the same drives?

I am trying to solve a dispute between a co-worker and myself so please answer quickly.

 

[J03]

Well, Im not sure myself. But the platter size could effect it, i'd imagine

 

[BrianS]

Ok, let me rephrase that. I have 3 hard drives set up in RAID 3. One of the hard drives died on us. I want to pull the bad one out, then put a new one in. Does the new one have to be the same as the other 2?

I personally think that any drive (as long as it meets the standards of the server itself like IDE or Serial ATA) would work.

 

[Atomic Rooster]

You could run a RAID 0 setup with different sized drives, but for your purposes, you'll need a matching drive to replace the bad drive. Preferably the same brand and model as the other two.

 

[root]

technically no, the drives don't have to be the same size.

but the array is only as big as the sum number of disks -1 (for parity) * the size of the smallest disk.

for example if you have four disks that are 500GB and 1 disk that is 250GB your array size is 4*250 = 1TB

if you have 4 500GB disks and 1 600GB disk your array size is 4*500GB = 2TB.

in the first example the remaining space on the first 4 500GB drives is not used, (250GB on each drive is wasted) in the second example 100GB on the fifth disk is not used (100GB is wasted).

for efficiency and not wasting space,(and money). all the drives should be the same size.
but they can be different.

(also).
they can be different kinds of disks.

if your array is software based there is no reason you couldn't mix IDE/SATA or even USB disks, (I imagine that the write speed is as fast as the slowest disk since data is split across all the disk at >1024 byte sizes.