Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Tom, you don't need to send the email to the list if you only have an issue with blktrace. It's easier to contact me directly for this. Regarding the command to produce some traffic: It is enough to produce e.g. 50 MB. For not using caching it's better to use direct IO. sudo dd if=/dev/zero of=/dev/vg0/test-io oflag=direct bs=1M count=50 The other issue is: blkparse collects the data from all CPU cores if called correctly. Please use the following instead: blkparse dm-4 | less blkparse drbd5 | less Then, you need to search for your "dd" process in the output. "flush-254:4" and "flush-147:5" are not what you are looking for. If you've got an FS on the device 4 KiB/8 sectors disk flushes are normal behaviour. As I wrote in the other topic: Big IO (512 KiB) e.g. on my raw desktop HDD sda looks like this: 8,0 1 177 34.431144943 1275 Q WS 94666752 + 1024 [dd] Cheers, Sebastian On 29.10.2012 15:19, Tom Fernandes wrote: > Hi Sebastian, > > Sorry for coming back only now. I ran the commands as suggested in the link on the local partition and on the DRBD-Partition. > > The output of blktrace / blkparse of the local partition: > tom at hydra04 [1609]:~/blkparse_dm-4_local$ sudo blktrace /dev/vg0/test-io -b 4096 & > [1] 8373 > tom at hydra04 [1610]:~/blkparse_dm-4_local$ pid=$! > tom at hydra04 [1611]:~/blkparse_dm-4_local$ sudo dd if=/dev/zero of=/dev/vg0/test-io bs=1M > dd: writing `/dev/vg0/test-io': No space left on device > 20481+0 records in > 20480+0 records out > 21474836480 bytes (21 GB) copied, 29.1139 s, 738 MB/s > tom at hydra04 [1612]:~/blkparse_dm-4_local$ sudo kill -2 $pid > tom at hydra04 [1613]:~/blkparse_dm-4_local$ === dm-4 === > CPU 0: 3941517 events, 184759 KiB data > CPU 1: 300485 events, 14086 KiB data > CPU 2: 63195 events, 2963 KiB data > CPU 3: 19456 events, 912 KiB data > CPU 4: 31830 events, 1493 KiB data > CPU 5: 0 events, 0 KiB data > CPU 6: 2900676 events, 135970 KiB data > CPU 7: 263447 events, 12350 KiB data > CPU 8: 88587 events, 4153 KiB data > CPU 9: 16105 events, 755 KiB data > CPU 10: 8225 events, 386 KiB data > CPU 11: 1856 events, 87 KiB data > CPU 12: 169875 events, 7963 KiB data > CPU 13: 71106 events, 3334 KiB data > CPU 14: 0 events, 0 KiB data > CPU 15: 0 events, 0 KiB data > CPU 16: 9416 events, 442 KiB data > CPU 17: 4507 events, 212 KiB data > CPU 18: 85902 events, 4027 KiB data > CPU 19: 7458 events, 350 KiB data > CPU 20: 0 events, 0 KiB data > CPU 21: 0 events, 0 KiB data > CPU 22: 0 events, 0 KiB data > CPU 23: 0 events, 0 KiB data > Total: 7983643 events (dropped 0), 374234 KiB data > tom at hydra04 [1613]:~/blkparse_dm-4_local$ blkparse dm-4.blktrace.0 | head > 254,4 13 1 0.000000000 8462 Q W 0 + 8 [flush-254:4] > 254,4 13 2 0.000027002 8462 Q W 8 + 8 [flush-254:4] > 254,4 13 3 0.000032502 8462 Q W 16 + 8 [flush-254:4] > 254,4 13 4 0.000035940 8462 Q W 24 + 8 [flush-254:4] > 254,4 13 5 0.000039489 8462 Q W 32 + 8 [flush-254:4] > 254,4 13 6 0.000042720 8462 Q W 40 + 8 [flush-254:4] > 254,4 13 7 0.000046493 8462 Q W 48 + 8 [flush-254:4] > 254,4 13 8 0.000050135 8462 Q W 56 + 8 [flush-254:4] > 254,4 13 9 0.000053015 8462 Q W 64 + 8 [flush-254:4] > 254,4 13 10 0.000055812 8462 Q W 72 + 8 [flush-254:4] > > > > The output of blktrace / blkparse on DRBD (which uses the logical volume from above as the backing device): > > tom at hydra04 [1616]:~/blkparse_drbd5_drbd$ sudo blktrace /dev/drbd/by-res/test-io -b 4096 & > [1] 10529 > tom at hydra04 [1617]:~/blkparse_drbd5_drbd$ pid=$! > tom at hydra04 [1618]:~/blkparse_drbd5_drbd$ sudo dd if=/dev/zero of=/dev/drbd/by-res/test-io bs=1M > dd: writing `/dev/drbd/by-res/test-io': No space left on device > 20480+0 records in > 20479+0 records out > 21474144256 bytes (21 GB) copied, 201.519 s, 107 MB/s > tom at hydra04 [1619]:~/blkparse_drbd5_drbd$ sudo kill -2 $pid > tom at hydra04 [1620]:~/blkparse_drbd5_drbd$ === drbd5 === > CPU 0: 60048 events, 2815 KiB data > CPU 1: 699195 events, 32775 KiB data > CPU 2: 642751 events, 30129 KiB data > CPU 3: 637215 events, 29870 KiB data > CPU 4: 483730 events, 22675 KiB data > CPU 5: 367882 events, 17245 KiB data > CPU 6: 533295 events, 24999 KiB data > CPU 7: 106050 events, 4972 KiB data > CPU 8: 20642 events, 968 KiB data > CPU 9: 7326 events, 344 KiB data > CPU 10: 1034 events, 49 KiB data > CPU 11: 1254 events, 59 KiB data > CPU 12: 7606 events, 357 KiB data > CPU 13: 9830 events, 461 KiB data > CPU 14: 2369 events, 112 KiB data > CPU 15: 0 events, 0 KiB data > CPU 16: 7022 events, 330 KiB data > CPU 17: 0 events, 0 KiB data > CPU 18: 89473 events, 4195 KiB data > CPU 19: 77342 events, 3626 KiB data > CPU 20: 0 events, 0 KiB data > CPU 21: 0 events, 0 KiB data > CPU 22: 0 events, 0 KiB data > CPU 23: 0 events, 0 KiB data > Total: 3754064 events (dropped 0), 175972 KiB data > tom at hydra04 [1620]:~/blkparse_drbd5_drbd$ blkparse drbd5.blktrace.0 | head > 147,5 13 1 0.000000000 10639 Q W 0 + 8 [flush-147:5] > 147,5 13 2 0.099943986 10639 Q W 8 + 8 [flush-147:5] > 147,5 13 3 0.099954085 10639 Q W 16 + 8 [flush-147:5] > 147,5 13 4 0.099959347 10639 Q W 24 + 8 [flush-147:5] > 147,5 13 5 0.099963852 10639 Q W 32 + 8 [flush-147:5] > 147,5 13 6 0.099969408 10639 Q W 40 + 8 [flush-147:5] > 147,5 13 7 0.099974688 10639 Q W 48 + 8 [flush-147:5] > 147,5 13 8 0.099980950 10639 Q W 56 + 8 [flush-147:5] > 147,5 13 9 0.099986854 10639 Q W 64 + 8 [flush-147:5] > 147,5 13 10 0.099992100 10639 Q W 72 + 8 [flush-147:5] > > > > There where 24 files produced by the blktrace command. I used the blkparse command on the first file as you can see. The RAID controller has read- and write-caching enabled. I'm not sure if this makes a difference. > > thanks and warm regards, > > > Tom