JaniD++ wrote: > > > > > > But the cat /dev/md31 >/dev/null (RAID0, the sum of 4 nodes) > > > > > > only makes ~450-490 Mbit/s, and i dont know why.... > > > > > > > > > > > > Somebody have an idea? :-) > > > > > > > > > > Try increasing the read-ahead setting on /dev/md31 using > > > > > 'blockdev'. network block devices are likely to have latency > > > > > issues and would benefit from large read-ahead. > > > > > > > > Also try larger chunk-size ~4mb. > > But i don't know exactly what to try. > increase or decrease the chunksize? > In the top layer raid (md31,raid0) or in the middle layer raids (md1-4, > raid1) or both? > What I found is that raid over nbd is highly max-chunksize dependent, due to nbd running over TCP. But increasing chunksize does not necessarily mean better system utilization. Much depends on your application request size. Tuning performance to maximize cat/dd /dev/md# throughput may only be suitable for a synthetic indication of overall performance in system comparisons. If your aim is to increase system utilization, then look for a good benchmark specific to your application requirements which would mimic a realistic load. -- Al - 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
