On Mon, 3 Mar 2008, Mark Mielke wrote:
> Has anybody been able to prove to themselves that RAID 0 vs RAID 1+0 is
> faster for these sorts of loads? My understanding is that RAID 1+0 *can*
> reduce latency for reads, but that it relies on random access, whereas RAID 0
> performs best for sequential scans? Does PostgreSQL ever do enough random
> access to make RAID 1+0 shine?
Theoretically the performance of RAID 0 and RAID 10 should be identical
for reads, both seeks and throughput, assuming you have a sensible
readahead and a good controller. For writes, RAID 10 needs to write to
multiple drives, so is slower. Whether this is true in reality is another
matter, as all sorts of factors come in, not least how good your
controller is at managing the arrangement.
Matthew
--
The only secure computer is one that's unplugged, locked in a safe,
and buried 20 feet under the ground in a secret location...and i'm not
even too sure about that one. --Dennis Huges, FBI