On 06/11/2014 11:49 AM, Stefan G. Weichinger wrote: > Am 11.06.2014 12:41, schrieb thegeezer: > >>> everything around 380 MB/s ... only ~350 MB/s for >>> /dev/vg01/winserver_disk0 (which still is nice) >> >> OK here is the clue. >> if the LVs are also showing such fast speed, then please can you show >> your command that you are trying to run that is so slow ? > I originally noticed that virt-backup was slow so I looked into it and > found some dd-command. > > My tests right now are like this: > > > > booze ~ # dd if=/dev/vg01/winserver_disk0 bs=1M of=/dev/null > ^C25+0 Datensätze ein > 24+0 Datensätze aus > 25165824 Bytes (25 MB) kopiert, 13,8039 s, 1,8 MB/s > > booze ~ # dd if=/dev/vg01/winserver_disk0 bs=4M of=/dev/null > ^C6+0 Datensätze ein > 5+0 Datensätze aus > 20971520 Bytes (21 MB) kopiert, 12,5837 s, 1,7 MB/s > > booze ~ # dd if=/dev/vg01/winserver_disk0 of=/dev/null > ^C55009+0 Datensätze ein > 55008+0 Datensätze aus > 28164096 Bytes (28 MB) kopiert, 12,611 s, 2,2 MB/s > > So no "copy from-to same disk here" ... should be just plain reading, right? > > virt-backup does some ionice-stuff as well, but as you see, my > test-commands don't. > > # cat /sys/block/sdc/queue/scheduler > [noop] deadline cfq > > -> noop scheduler to let the controller do its own scheduling > > > > thanks, Stefan > > >
just out of curiosity, what happens if you do # dd if=/dev/vg01/amhold of=/dev/null bs=1M count=100 # dd if=/dev/sdc of=/dev/null bs=1M count=100
