[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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