[DRBD-user] slow disk throughput

William Francis wfrancis at gmail.com
Tue Jun 17 20:01:32 CEST 2008

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

I upgraded my drbd kernel module and userland tools to 8.0.12 and added 
the two additional parameters to my disk section of my drbd.conf as Lee 
suggested and wow, a full 10X improvement in write speed, which is about 
60% of bare metal speed.

What does this suggest? Does 8.0.11 have some performance ....um, issues 
(or perhaps just the version that ships with Ubuntu Hardy?) or does it 
not just work well with my hardware? Or is the slower speed expected if 
one wants to operate with maximum safety?  But I think I read that 7.x 
got about 60% bare metal speed? hmmm.

either way, I now have a config that works, thanks!


Florian Haas wrote:
> Florian Haas wrote:
>> William, Lee,
>> William Francis wrote:
>>>> Raw throughput on the same RAID10 array, non-drbd partition:
>>>> time dd if=/dev/zero of=/tmp/delete/out.file bs=1M count=5000
>> You're not measuring throughput. You're measuring a mixture of
>> throughput and latency, and not that of your disk but that of your page
>> cache.
>> Also, you didn't give us much information about your underlying storage
>> subsystem (SCSI or SATA, BBWC or not, disk speed & capacity, etc.). The
>> DRBD version you are using would also be very helpful.
> Oops, sorry. Saw your other email just now. OK so we already know the
> DRBD version. Apologies :-)
> Cheers,
> Florian

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