[DRBD-user] Re: strange performance problems with drbd

Torsten Neumann Torsten.Neumann at dlh.de
Mon May 8 17:01:08 CEST 2006

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 <Lars.Ellenberg at ...> writes:

> > So how can I check why drbd slows things so terrible down? Yes there is a
> > bottleneck. But without drbd all seems fine, with drbd not.
> see what io scheduler is in use
> (/sys/block/lower-level-device/queue/scheduler)
> on servers I prefer "deadline".
> you can switch to "deadline" like this:
>   for q in /sys/block/*/queue/scheduler ; do
> 	echo deadline > "$q"
>   done
> or by specifying a boot-time commandline parameter.
> if that did not help yet,
> check wether increasing "max-buffers"
> and/or decreasing "max-epoch-size" in drbd.conf does help.

Neither changer io scheduler from anticipatory to deadline nor lowering
max-epoch-size showed any effect. max-buffers was on the highest allowed value
anyway. But decreasing didn't helped also.

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