Messages in this thread | | | From | Al Boldi <> | Subject | Re: io-scheduler tuning for better read/write ratio | Date | Wed, 24 Jun 2009 10:57:41 +0300 |
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Ralf Gross wrote: > The main problem is with bacula. It reads/writes from/to two > spoolfiles on the same device. > > I get the same behavior with 2 dd processes, one reading from disk, one > writing to it. > > Here's the output from dstat (5 sec intervall). > > --dsk/md1-- > _read _writ > 26M 95M > 31M 96M > 20M 85M > 31M 108M > 28M 89M > 24M 95M > 26M 79M > 32M 115M > 50M 74M > 129M 15k > 147M 1638B > 147M 0 > 147M 0 > 113M 0 > > > At the end I stopped the dd process that is writing to the device, so you > can see that the md device is capable of reading with >120 MB/s. > > I did this with these two commands. > > dd if=/dev/zero of=test bs=1MB > dd if=/dev/md1 of=/dev/null bs=1M
Try changing /proc/sys/vm/dirty_ratio = 1
Thanks!
-- Al
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