Hi, I can't help with your issue but I can give some comments on your testing:
On Tuesday 23 October 2012 12:12:26 Tom Fernandes wrote: > tom@hydra04 [1522]:~$ sudo dd if=/dev/zero of=/mnt/test-io/test.dd bs=1M > count=5000 > 5000+0 records in > 5000+0 records out > 5242880000 bytes (5.2 GB) copied, 13.8065 s, 380 MB/s That test is rubbish. When you want to test with dd (which only gives you the write-rate for sequential access) you have to use oflag=sync, otherwise you will see the caching of fs and disk-layer. You should test with a multiple of 4M block-size, otherwise half your writing 1MB will be reading the other 3MB of the block. > tom@hydra04 [1523]:~$ sudo nc 10.0.0.2 1234 < /mnt/test-io/test.dd > # Summary: > # Piped 4.88 GB in 00h00m22.37s: 223.45 MB/second > ---------------------------------------------------------------------- I use iperf for this, easier commandline. > ----- bonnie on local partition on hydra04 - hydra05 is the same --------- > tom@hydra04 [1498]:~$ sudo mount /dev/vg0/test-io /mnt/test-io/; cd > /mnt/test-io/; time sudo bonnie -f -u root; cd -; sudo umount /mnt/test-io/ > Using uid:0, gid:0. > Writing intelligently...done > Rewriting...done > Reading intelligently...done > start 'em...done...done...done...done...done... > Create files in sequential order...done. > Stat files in sequential order...done. > Delete files in sequential order...done. > Create files in random order...done. > Stat files in random order...done. > Delete files in random order...done. > Version 1.96 ------Sequential Output------ --Sequential Input- -- > Random- > Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- -- > Seeks-- > Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec > %CP > hydra04 96704M 495967 68 159106 20 546991 28 > 727.7 11 > Latency 203ms 940ms 183ms > 186ms Version 1.96 ------Sequential Create------ --------Random > Create-------- > hydra04 -Create-- --Read--- -Delete-- -Create-- --Read--- - > Delete-- > files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec > %CP > 16 5425 6 +++++ +++ 20766 23 +++++ +++ +++++ +++ +++++ > +++ > Latency 478us 707us 685us 339us 18us > 724us > 1.96,1.96,hydra04,1,1350881245,96704M,,,,495967,68,159106,20,,,546991,28,72 > 7.7,11,16,,,,,5425,6, +++++,+++,20766,23,+++++,+++,+++++,+++,+++++, > +++,,203ms,940ms,,183ms,186ms,478us,707us,685us,339us,18us,724us Another interesting test is dbench which simulates windows-sessions with access from word, excel and ms access. And the results of both bonnie and dbench are far more realistic then of simple dd, because doing long sequential reads is a special case only known in audio/video reproduction. And even there it might be that several streams are mixed and thus several different files at different positions are accessed interleaved. For office, email, database, webserver its never reading big chunks sequentially, its aleays about reading a bit here and a bit there and be low latency (aka seek time) with this, not high throughput in raw bandwidth. Have fun, Arnold
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