[DRBD-user] Slow Access

gilberto.nunes gilberto.nunes at selbetti.com.br
Tue Oct 27 17:58:49 CET 2009

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


I just do some test...
But in a real enviroment this performance is preocuped...
Is there some way "allow-two-primaries" work on Protocol A.


On Tue, 27 Oct 2009 14:36:11 +0100, Stefan Seifert <nine at detonation.org>
> On Tuesday 27 October 2009 15:09:02 gilberto.nunes wrote:
>> Drbd works fine but I attempt
>> deploy virtual machine with KVM and I feel access to /dev/drb0 is
>> slowing...
> So you've got two VMs running on the same host and sharing a drbd disk?
> That will never be fast even if you do all the performance tuning that's

> documented in the user's guide, the performance seminar, Flo's blog and
> this 
> mailing list.
> Virtualization already slows down I/O access dramatically, because for
> every 
> little request there are a few context switches involved. Same goes for 
> networking. With drbd you double your I/O requests and add networking on
> top 
> of it. That's all the slowness you could possibly find on your system 
> combined.
> Using protocol A might improve the situation but with the obvious 
> disadvantages. But I assume this setup is only for testing anyway? So
> don't 
> worry too much about performance now and get on to optimizing when it's 
> deployed on real hardware. Should make a huge difference.
> Regards,
> Stefan

Gilberto Nunes Ferreira
Selbetti Gestão de Documentos
Telefone: +55 (47) 3441-6004
Celular: +55 (47) 8861-6672 


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