[DRBD-user] DRBD resync QoS

Digimer linux at alteeve.com
Wed Jun 22 04:28:55 CEST 2011

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

On 06/21/2011 09:51 PM, wang xuchen wrote:
> Digimer,
> Thanks for your reply.
> I come up with the number 300M from DRBD official website "A good rule
> of thumb for this value(rate parameter) is to use about 30% of the
> available replication bandwidth. ". I use 10G Ethernet card for
> replication traffic, 1024M * 0.3 is 300M. What wrong with my calculation?
> Ben

That is your network speed. Have you calculated your maximum disk I/O?

During resync, you should see how quickly the resync is running at. Is 
it actually going at ~300MB/sec? If your IO is well over 300MB/sec, then 
I am not sure off hand what is causing the slowdown.

Are all ten DRBD resources on the same set of drives? If so, then 
perhaps the disks' read/write heads are flogged? To test, can you 
'pause-sync' on all but one resource at a time and see if performance 
returns? If it does, then resume-sync one resource at a time and see at 
what point the performance becomes unacceptable.

E-Mail:              digimer at alteeve.com
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