[DRBD-user] Full write speed on local disks and network but slow write-speed on drbd

Sebastian Riemer sebastian.riemer at profitbricks.com
Tue Oct 23 17:09:25 CEST 2012

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


Hi Tom,

there was already a similar discussion. It would be a big help if you
trace your IOs in the blkio layer.

http://www.mail-archive.com/drbd-user@lists.linbit.com/msg06705.html

Use the tool "blktrace" for that. If IOs are too small, then this has
the biggest impact on performance. E.g. software bugs can cause IOs to
be too small.

Cheers,
Sebastian

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Sebastian Riemer
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On 23.10.2012 12:12, Tom Fernandes wrote:
> I'm experiencing a strange and interesting issue. I have a two-node-cluster 
> with write-speed on a local partition of ~500MB/s and network throughput of 
> ~220MB/s. But when writing to the drbd-partition I get only ~60MB/s. Another 
> interesting thing is, that the initial-sync-speed reported by "watch cat 
> /proc/drbd" is roughly 215MB/s. Also the seeks/s are a lot slower on the drbd-
> partition - which makes me worry as this cluster is also meant to run a 
> database.





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