[DRBD-user] performance issue when writing to drbd devices

Felix Frank ff at mpexnet.de
Fri Sep 27 12:02:38 CEST 2013

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


Hi,

On 09/26/2013 05:23 PM, Matthias Teege wrote:
> - no fancy drbd tunables set (e.g. "rate")

heh, "fancy"? If you didn't touch any tuning parameters, low performance
isn't all that miraculous.

> - local logical volume -> local logical volume: FAST writing speeds
> - local LVM2 logical volume -> local drbd device: SLOW writing speeds
> 
> Any ideas what could eat up our performance while writing to a local
> drbd device?

Look at this: http://www.drbd.org/users-guide/ch-throughput.html

I think the activity log may be especially promising for your scenario.
If you have battery or flash backup for your RAID, definitely look at
flush and drain options.

HTH,
Felix



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