Re: RAID 1 or RAID 10?

Ric wrote:
> Just about to set up our new Oracle server. The box is a Dell PowerEdge
> 2850, Dual Xeon 3.6GHz with 4 Gb RAM and 4x 18Gb 15,000 RPM Drives. I am
> about to set up the RAID array and am unsure as what would be best. I was
> originally going to use RAID 5 but am unsure now as I have read so many bad
> things about using it with Oracle. Some form of redundancy is requred so
> here are my proposed alternatives:
>
> 1) 2x RAID 1 arrays - this would give me a total of 36Gb and as each volume
> would be mirrored I would have the necessary fault tolerance. I could then
> split data across the two arrays, i.e. Windows Server 2003 and system files
> on one and data files on the other
>
> 2) 1x RAID 10 array - this would have the data striped over two disks which
> would be mirrored to provide the fault tolerance. I would only have one
> volume but there would be a performance increase due to the striping. I'm
> not sure if there is much worth to having a stripe set with only two disks.
>
> Any strong feelings or opinions?
>
> Thanks.
>

With just 4 drives, I would go RAID5. Probably.

The horror stories you've read about RAID5 need to be read in context. And then you need to realise the context you are in -namely, fairly low-end hardware and not many hard disks. The horror stories probably do not apply to the situation you find yourself in.

The decision might also depend, however, on what you intend doing with this database. Is it warehouse, or OLTP? 10 users or 1000? Clearly, your data volumes are not going to be very high, but the rest is just guesswork.

If you care to describe some of the "bad things" you've read about RAID5, then I'm sure a reasoned discussion of them here could either confirm some doubts or dispell others.

But dismissing all RAID 5 'on principle' is as bad as routinely rebuilding all your indexes, or thinking that I/O bottlenecks have been eliminated because you've stored tables and indexes in separate tablespaces: it's a sweeping generalisation that can cause grief.

Regards
HJR Received on Tue Dec 21 2004 - 13:08:39 CST