[DRBD-user] Userspace- vs. Kernelspaceversions

Andreas Kurz andreas at hastexo.com
Wed Nov 30 17:20:19 CET 2011


On 11/30/2011 05:03 PM, Arnold Krille wrote:
> Hi all,
> 
> I am a bit stumped currently. Our drbd setup seems to include "extra low 
> performance" as a feature and I don't exactly know where the reason is.
> On thing the bothers bothers us is that the versions of the userspace tools 
> and the kernel module differ (drbd8-utils v8.3.7 vs module v8.3.9).
> The newer kernel-module is a side-effect of the kernel from debian squeeze 
> backports needed for the new network-cards. But the versions installed on both 
> nodes are the same.
> Using latency- and throughput tests from the drbd documentation, the latency 
> rises by a factor of ten and the throughput sinks by a factor of ~5 from the 
> baccking devices to the drbd device.

What does your drbd config look like? How did you test? What is your
current drbd state ... cat /proc/drbd?

> 
> So here are my questions:
>  - Could the mixed version be the reason for the performance penalty?

No.

>  - Would it be save to downgrade the kernel (and compile the network-driver by 
> hand) or is the meta-data on the disk incompatible?
>  - Or would you rather update the userspace tools to match the modules 
> version?

I would upgrade drbd module _and_ usertools to latest 8.3.12. ... 8.3.9
has a know regression that affects small synchronous writes, that may be
an explanation for the increased latency.

Regards,
Andreas

-- 
Need help with DRBD?
http://www.hastexo.com/now

> 
> Thanks for any answers,
> 
> Arnold
> 
> 
> 
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> drbd-user at lists.linbit.com
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