>>>While I agree about RAID 0, RAID 5 is a different thing. I see it as BOTH performance and protection. But of course it costs.
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>>A new RAID 5+0 is performance & protection, RAID 5 is pure protection. That's why you can run RAID 5 with only 3HD while RAID 5+0 cannot!
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>Well I'm only going on an experience with a RAID 5 "Storageworks" unit 6+ years ago hooked to Novell 3.x and I can tell you it was FAST. Unbelievably so, in my opinion.
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>vheers
>
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>>Regards

The following is a simplified explanation. On RAID 5, with the standard 3 disks (I believe other arrangements are possible), half of the data is on the first disk, and half on the second disk, while the third disk is redundancy (obtained through XOR, I believe).

If you have half of the data on each of two disks, it seems quite logical that the data can be read up to twice as fast.

In summary, RAID 5 is not only for protection. It gives you:

Protection. Any one of the 3 hard disks can fail, and be replaced by another one of the same size.

Speed. See above.

Unlike mirroring, only 1/3 of the total capacity is wasted.

Hilmar.

Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)