[DRBD-user] Write performance 0.7.4 versus 0.7.5 on Primary +SyncTarget

Todd Denniston Todd.Denniston at ssa.crane.navy.mil
Tue Oct 5 18:23:53 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Lars Ellenberg wrote:
> / 2004-10-05 17:59:08 +0200
> \ Bernd Schubert:
> > On Tuesday 05 October 2004 17:13, Benoit.Ropartz at alcatel.fr wrote:
> > > Ok i have tested writes speed during normal operation and i got sames
> > > results
> > > with two versions ~ 600 Ko/s.
> > >
> > > But why i find difference when syncing is active (30ko=>2ko) ???
> >
> > Just read the changelog of 0.7.5, the write speed barrier of 30MB/s has gone
> > with this version. Probably you are now syncing with the full speed of your
> > hardware (check the logs or /proc/drbd during the synchronisation to get the
> > sync speed) and with the previous version only at 30MB/s and so there was l
> > more capacity left for normal writing operation.
> right.
> thanks for answering those questions.
Just did some looking on the net. What happened to sync-nice (from 0.6.x),
does it have an upgrade (0.7.x) counterpart?
The reason I ask is that with our setup I found setting sync-max to just under
the max our hardware would support and sync-nice to 1, got a nice mix of fast
syncing when everyone is at home, but a machine that responds reasonably fast
even while syncing during the day.

Oh, and understand like Bernd Schubert was saying sync group maters, if you
have just one physical device. Although I have a box doing raid5 with 5
drives, the raid5 device is still a single physical device. Head seek to
different partitions was trashing my sync speed.
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane) 
Harnessing the Power of Technology for the Warfighter

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