Slow Access

[Gilberto Nunes-3]

Hi buddies

I have make a server here, with two nodes, with Ubuntu 9.04.

I config the drbd8-utils, version 2:8.3.0-1ubuntu1, with this conf on both nodes:

obal { usage-count no; }
common { syncer { rate 30M; } }
resource r0 {
        protocol C;
        startup {
                wfc-timeout 15;
                degr-wfc-timeout 60;
                become-primary-on both;
        }
        net {
                cram-hmac-alg sha1;
                shared-secret "drbd123";
                allow-two-primaries;
                after-sb-0pri discard-zero-changes;
                after-sb-1pri discard-secondary;
                after-sb-2pri disconnect;
        }
        on kvm-0 {
                device /dev/drbd0;
                disk /dev/sda7;
                address 10.0.0.10:7788;
                meta-disk internal;
        }
        on kvm-1 {
                device /dev/drbd0;
                disk /dev/sda7;
                address 10.0.0.100:7788;
                meta-disk internal;
        }
}

Drbd works fine but I attempt deploy virtual machine with KVM and I feel access to /dev/drb0 is slowing...

Nothing to desperate, but a instalation of Windows 2003 take some many times! About 2 hours..

I don't know what going happen here!!!

Thanks for any advice

 

Regards

 

--

Gilberto Nunes Ferreira
TI
Selbetti Gestão de Documentos
Telefone: [phone]
Celular: [phone] 



"Bendita a nação cujo Deus é o Senhor!"
<><

_______________________________________________
drbd-user mailing list
drbd-user@...
http://lists.linbit.com/mailman/listinfo/drbd-user

[Stefan Seifert-3]

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


_______________________________________________
drbd-user mailing list
drbd-user@...
http://lists.linbit.com/mailman/listinfo/drbd-user

[Gilberto Nunes-3]

Yes

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.

Thanks

On Tue, 27 Oct 2009 14:36:11 +0100, Stefan Seifert <nine@...>
wrote:
> 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
TI
Selbetti Gestão de Documentos
Telefone: [phone]
Celular: [phone]

_"BENDITA A NAO CUJO DEUS  O SENHOR!"_
<
_______________________________________________
drbd-user mailing list
drbd-user@...
http://lists.linbit.com/mailman/listinfo/drbd-user