[DRBD-user] drbd 'none' io scheduler

Felix Frank ff at mpexnet.de
Wed Dec 7 17:53:42 CET 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 12/07/2011 04:55 PM, Adam Kliment wrote:
> Hello,
> I'm fighting with weird issue. When I was tweaking IO scheduling and QoS
> with ionice I took notice that there is written "none" inside of all
> drbd's scheduler nodes in sysfs (/sys/block/dbrd*/queue/scheduler). It
> seem's like no io scheduler is available fot drbd devices at all. Could
> anybody explain me what does it mean, please? I think it's in conflict
> with chapter 13.3.3 of documentation which is about setting io scheduler
> for drbd resource to "deadline" to improve io performance.
> Btw writing 'cfq' or whatever to that file has no effect. Details here:
> http://pastebin.com/77FNEfxG
> Many thanks!

I'm pretty sure you're supposed to work with the scheduler for your
backing device. Scheduling both backing storage and DRBD would be madness.

AFAIK, ionice doesn't do much unless you're using CFQ, which in many use
cases you shouldn't. Of course, your setup may differ.


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