[DRBD-user] Control syncer speed

matt matt at linbit.com
Tue Apr 6 19:35:05 CEST 2021

On 3/31/21 2:32 AM, Michael Hierweck wrote:
> Hi all,
> with DRBD 9.0.25 we experience problem with the syncer rate.
> Using default settings our IO system gets overloaded, especially when 
> multiple resources are be resynced in parallel.

It's possible to configure "serialized resyncs" by setting the 
"resync-after" disk option.

For example, to suspend r1's resync until r0 has completed it's resync, 
you would set the following:

resource r1 {
     disk {
         resync-after r0;

> Neither
> drbdadm peer-device-options --c-plan-ahead=X --c-max-sync-rate=Y <res>

The setting to limit the maximum rate of resync is 'c-max-rate', not 
'c-max-sync-rate'. Maybe that helps, or is just a typo in your email.

> drbdadm peer-device-options --c-plan-ahead=0 --resync-rate=Y <res>
If I recall correcly, since DRBD 8.4.0 the 'resync-rate' is used as a 
"starting point" for the dynamic resync controller, so I'm not sure 
setting that will have a meaningful effect.

Matt Kereczman – Solutions Architect
+1 503 573-1262 x205
matt at linbit.com

LINBIT | Keeping the Digital World Running
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