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On my work PC, I'm running a RAID 1 currently.

I have an opportunity to upgrade my system and I'm wondering what is the best setup I can use.

I have 4 available hard drives and I definitely need fault-tolerance. I heard that RAID 10 is better than RAID 5.

Which configuration should I go with?

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Raid 10 is better than raid5

  • Raid 5 you can lose at most one disk
  • Raid 10 you can lose two disks as long as they're not from the same pair
  • Raid 10 is faster

Personally, I feel raid5 is a bit of a waste on 4 disks - it leaves you with the capacity of n-1 disks whereas raid10 gives you a capacity of n/2 disks. If you have 10 disks then there's a sigificant amount of space lost by choosing raid10, but with 4 disks it's not nearly as significant.

If you can afford to give up the extra space then go with raid 10.

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Well, RAID 10 is certainly the "Rolls-Royce" of RAID configruations. Guess it really boils down to a) do I really feel I need it, and b) can I afford to buy that many disks... – marc_s Jul 15 '09 at 16:08
c) Does my RAID adapter support RAID10? – Russ Warren Jul 15 '09 at 16:12
"raid5 is a bit of a waste on 4 disks" - more than that: on an array this small, it's outright dangerous ( en.wikipedia.org/wiki/RAID_5_write_hole et al) when compared to RAID 10. – Piskvor May 2 at 14:54
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Raid 10 is a massive waste of space, and the benefits you might get in redundancy can be just as easily achieved with sort sort of offsite or cloud backup. Raid 5 is usually good enough since it's only really broken if two drives fail, which is extremely rare.

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If you had 4 500gb disks, then you're looking at a total usable space of 1.5gb vs 1gb (for raid5 vs. raid10). That isn't really a massive waste of space for something that will be faster. – theotherreceive Jul 15 '09 at 16:10
I guess that depends how big your work's hardware budget is... – user1509 Jul 15 '09 at 16:14
"if two drives fail, which is extremely rare" - this is only rare if your disks are uncorrelated. Example: we bought a server with 4 disks, all were from the same batch, one failed after ~1000 hours, another a few hundred hours later. A bad batch, probably (manufacturer replaced them without any opposition at all, I suspect we weren't the only ones affected; the other two are still in service AFAIK). – Piskvor May 2 at 14:59
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