On Monday November 29, raid@xxxxxxxx wrote: > > now i get 275MB/sec with raid0 (14 disks) > 171MB/sec with raid5 (14 disks) > > while the old raid5 situation was 257MB/sec with raid5 (13 disks) I presume you are only looking at 'read' speed here. There is a read optimisation that I haven't implemented in 2.6 yet that could account for about a 10% difference, but a 30% difference definitely surprises me. Normally raid5 will read into the stripe cache, and then copy data out of the stripe cache and into the request buffer for reads. The optimisation is to read directly into the request buffer in situations where no degraded stripes or pending write requests. This optimisation is implemented in 2.4 and gave me about a 10% speedup on sequential reads. Its substantially more complicated in 2.6... I might do a bit of testing myself, but more results from others would be helpful... NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
