On 06/11/2014 12:21 PM, Stefan G. Weichinger wrote: > Am 11.06.2014 13:18, schrieb thegeezer: > >> 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 > > > booze ~ # dd if=/dev/vg01/amhold of=/dev/null bs=1M count=100 > 100+0 Datensätze ein > 100+0 Datensätze aus > 104857600 Bytes (105 MB) kopiert, 1,71368 s, 61,2 MB/s > > booze ~ # dd if=/dev/sdc of=/dev/null bs=1M count=100 > 100+0 Datensätze ein > 100+0 Datensätze aus > 104857600 Bytes (105 MB) kopiert, 2,40518 s, 43,6 MB/s > >
ok baffling. sdc i already said would be slower but not this much slower it certainly should not be slower than the lvm that sits on top of it! i can't see anything in the cgroups that stands out, maybe someone else can give a better voice to this. all i can think is there is other IO happening in atop if you can highlight any line that begins LVM CPU or DSK and paste it in to a reply - with no virtualmachines running and no dd or anything. then run a dd as before and highlight the lines in atop while it is running (maybe increase count to 1000 to give yourself a chance) and paste in here too
