On 06/08/10 11:58, Alan Hodgson wrote:
On Thursday, August 05, 2010, Mark Kirkwood<mark.kirkwood@xxxxxxxxxxxxxxx>
wrote:
Normally I'd agree with the others and recommend RAID10 - but you say
you have an OLAP workload - if it is *heavily* read biased you may get
better performance with RAID5 (more effective disks to read from).
Having said that, your sequential read performance right now is pretty
low (151 MB/s - should be double this), which may point to an issue
with this controller. Unfortunately this *may* be important for an OLAP
workload (seq scans of big tables).
Probably a low (default) readahead limitation. ext3 doesn't help but it can
usually get up over 400MB/sec. Doubt it's the controller.
Yeah - good suggestion, so cranking up readahead (man blockdev) and
retesting is recommended.
Cheers
Mark
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