Re: RAID Levels

The term "level" when dealing with RAID, IMO, is a misnomer. This tends to mean that one level is "higher" than another. But I digress...

RAID 0 is not true RAID in that it does not provide any redudancy. It only stripes the data across multiple disk volumes.

RAID 1 performs mirroring. It makes a duplicate. RAID 1 is pretty good for write intensive software like Oracle.

Many people prefer the redundancy of mirroring, coupled with the speed of striping so they combine RAID 0 and RAID 1 to get RAID 0+1. This may be what you are referring to as RAID 10.

The downside of any RAID 1 implementation is that requires twice as much disk. But you get great performance. To save on disk, many people like RAID 5. RAID 5 stripes the data across multiple volumes and it stores parity bits on the disks as well to help with redudancy. RAID 5 does suffer from a write penalty. Your write operations can take twice as long. So many DBAs stay away from RAID 5 if at all possible.

RAID 3 is similar to RAID 5 in that it stripes and stores parity bits. But the parity bits are stored on a special volume. So the write performance isn't as bad as RAID 5.

HTH,
Brian

Hari Om wrote:
>
> Which RAID Level is usually best for any DB...? Level 0,1 5 or 10?
> Which type is better...Hardware or Software RAID?
>
> Any related information is appreciated!
>
> Thanks!

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Brian Peasland
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