[DRBD-user] write performance issues

Felix Frank ff at mpexnet.de
Mon Jul 11 10:11:31 CEST 2011

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

On 07/08/2011 03:00 PM, Mark Dokter wrote:
> I already did quite some research on that issue (that's how I came up
> with that DRBD config), but didn't succeed in fixing it. Maybe someone
> on this list has suggestions?

It's possible that your Secondary is slowing you down.

Could there be any weirdness going on with its RAID (there was recently
a poster who had nearly-undetectable BBU issues)?

What IO schedulers are the nodes using? If CFQ, change it.

There can be other mean performance surprises, such as barrier
synchronization being incredibly slow on certain platforms for no
conceivable reason.

I also notice that your syncer rate is quite high. As this is a Gigabit
uplink, you may want to go as low as 30M, as 110 can bog down your link.
Why is the DRBD link switched?


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