Why raid10 driver from Centos 6 has a 300% slower random write performance (random read stays the same) than Centos 5? I run tests on centos 5. ./seekmark -f /dev/md3 -t 8 -s 1000 -w destroy-data WRITE benchmarking against /dev/md3 1838736 MB threads to spawn: 8 seeks per thread: 1000 io size in bytes: 512 write data is randomly generated Spawning worker 0 to do 1000 seeks Spawning worker 1 to do 1000 seeks Spawning worker 2 to do 1000 seeks Spawning worker 3 to do 1000 seeks Spawning worker 4 to do 1000 seeks Spawning worker 5 to do 1000 seeks Spawning worker 6 to do 1000 seeks Spawning worker 7 to do 1000 seeks thread 5 completed, time: 39.75, 25.16 seeks/sec, 39.8ms per request thread 1 completed, time: 40.99, 24.39 seeks/sec, 41.0ms per request thread 7 completed, time: 41.35, 24.18 seeks/sec, 41.4ms per request thread 4 completed, time: 41.59, 24.04 seeks/sec, 41.6ms per request thread 2 completed, time: 41.69, 23.99 seeks/sec, 41.7ms per request thread 3 completed, time: 41.90, 23.87 seeks/sec, 41.9ms per request thread 0 completed, time: 42.23, 23.68 seeks/sec, 42.2ms per request thread 6 completed, time: 42.24, 23.67 seeks/sec, 42.2ms per request total time: 42.26, time per WRITE request(ms): 5.282 189.31 total seeks per sec, 23.66 WRITE seeks per sec per thread Then installed centos 6 (the same kickstart just ISO changed) preserving partitons. I created raid10 with the same command as on centos 5 (mdadm -C /dev/md3 -e0.9 -n4 -l10 -pf2 -c2048 /dev/sda4 /dev/sdb4 /dev/sdc4 /dev/sdd4) When resync completed I run the same test command and got: WRITE benchmarking against /dev/md3 1838736 MB threads to spawn: 8 seeks per thread: 1000 io size in bytes: 512 write data is randomly generated Spawning worker 0 to do 1000 seeks Spawning worker 1 to do 1000 seeks Spawning worker 2 to do 1000 seeks Spawning worker 3 to do 1000 seeks Spawning worker 4 to do 1000 seeks Spawning worker 5 to do 1000 seeks Spawning worker 6 to do 1000 seeks Spawning worker 7 to do 1000 seeks thread 5 completed, time: 118.53, 8.44 seeks/sec, 118.5ms per request thread 7 completed, time: 122.78, 8.14 seeks/sec, 122.8ms per request thread 3 completed, time: 124.16, 8.05 seeks/sec, 124.2ms per request thread 0 completed, time: 125.71, 7.95 seeks/sec, 125.7ms per request thread 6 completed, time: 125.75, 7.95 seeks/sec, 125.7ms per request thread 4 completed, time: 125.78, 7.95 seeks/sec, 125.8ms per request thread 2 completed, time: 126.58, 7.90 seeks/sec, 126.6ms per request thread 1 completed, time: 126.80, 7.89 seeks/sec, 126.8ms per request total time: 126.81, time per WRITE request(ms): 15.851 63.09 total seeks per sec, 7.89 WRITE seeks per sec per thread I recreated the array with all mdadm metas (0.9 1.2 1.1) - still the same poor random write performance. Please share your ideas. -- 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
