On Wed, Nov 05, 2008 at 08:13:10AM +0100, Christian Schröder wrote:
> Tomasz Ostrowski wrote:
> >This is wrong. RAID5 is slower than RAID1.
> >You should go for RAID1+0 for fast and reliable storage. Or RAID0 for
> >even faster but unreliable.
> >
> I did not find a clear statement about this. I agree that RAID10 would
> be better than RAID5, but in some situations RAID5 at least seems to be
> faster than RAID1.
The basic problem is that RAID5 has a checksum disk. So if you update a
block, you need to update the checksum. No matter how you do it you
need to read one or more of the parallel blocks. Clever disk
controllers can reduce the cost, but not eliminate it. None of RAID 0, 1
or 10 have this problem.
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
> boarding. Thank you for flying nlogn airlines.