drbd-user March 2010 archive
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drbd-user: Re: [DRBD-user] DRBD is deadly slow.

Re: [DRBD-user] DRBD is deadly slow.

From: Stefan Seifert <nine_at_nospam>
Date: Tue Mar 30 2010 - 13:50:39 GMT
To: drbd-user@lists.linbit.com

> 2010/3/30 Balreddy Medipally <balreddy.m@imimobile.com>
>
> > I am running DRBD 8.3.0 on RedHat Enterprise Linux AS 4.8 64-bit
> > OS for production purpose. MySQL works superfast in when load was not
> > there, when load was there it become deadly slow. Can any one please
> > help me to make it faster.

On Tuesday 30 March 2010 15:35:06 PN wrote:
> Try to increase the syncer rate to a much higher number and restart DRBD on
> both nodes will definitely help to increase the sync speed.

If the volumes are in sync the sync speed should not affect DRBD performance
in any way. And if they are not in sync, raising sync speed would even make
the performance worse, since DRBD would spend more resources on resync and
less on the application's workload!

This sounds more like something for the DRBD performance tuning webinar.
Tuning of al-extents, network parameters and the like. Also if a battery
backed RAID controller is being used (and it should):
    no-disk-barrier;
    no-disk-flushes;
    no-md-flushes;
can be used which make a huge difference in writing performance. But in any
case the webinar and some good benchmarking should be the first step.

Regards,
Stefan
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