On Sat October 31 2009, Jon Nelson wrote: > I have a 4 disk raid6. The disks are individually capable of (at > least) 75MB/s on average. > The raid6 looks like this: > > md0 : active raid6 sda4[0] sdc4[5] sdd4[4] sdb4[6] > 613409536 blocks super 1.1 level 6, 64k chunk, algorithm 2 [4/4] > [UUUU] > > The raid serves basically as an lvm physical volume. > > While rsyncing a file from an ext3 filesystem to a jfs filesystem, I > am observing speeds in the 10-15MB/s range. > That seems really really slow. > > Using vmstat, I see similar numbers (I'm averaging a bit, I'll see > lows of 6MB/s and highs of 18-20MB/s, but these are infrequent.) > The system is, for the most part, otherwise unloaded. > > I looked at stripe_cache_size and increased it to 384 - no difference. > blockdev --getra reports 256 for all involved raid components. > I'm using the deadline I/O scheduler. > > Am I crazy? Is 12.5MB/s (average) what I should expect, here? What > might I look at here? > I can't say I see numbers that bad.. But I do get 1/3 or less of the performance with .29, .30, .31, and .32 than I get with .26. I haven't tried any other kernels as these are the only ones I've been able to grab from apt ;) I get something on the order of 100MB/s write and read with newer kernels, with really bursty behaviour, and with .26, its not as fast as it COULD be, but at least I get 200-300MB/s, which is reasonable. Now if your two file systems are on the same LVM VG, that could have an impact on performance. -- Thomas Fjellstrom tfjellstrom@xxxxxxx -- 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
