Yes write cache is on the drives and the comparisons are all with the same hardware... apples for apples and no pears ;) Write is often faster (in my mind) simply because you can use a lot of write cache (in system)... whilst reads reads you are limited to what the drives can pull off. I also guess that the FS's - mainly ext2 it seems is more effecient at implementing a read cache than a raw device, hence the slight performance increase.... but i just guessing to be honest On Wed, Nov 4, 2009 at 7:05 PM, Steve Cousins <steve.cousins@xxxxxxxxx> wrote: > mark delfman wrote: >> >> Some FS comparisons attached in pdf >> >> not sure what to make of them as yet, but worth posting >> > > I'm not sure either. Two things jump out. > > 1. Why is raw RAID0 read performance slower than write performance > 2. Why is read performance with some file systems at or above raw read > performance? > > For number one, does this indicate that write caching is actually On on the > drives? > > Are all tests truly apples-apples comparisons or were there other factors in > there that aren't listed in the charts? > > I guess these issues might not have a lot to do with your main question but > you might want to double-check the tests and numbers. > > Steve > -- 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
