[DRBD-user] Forcing a device to be primary on a backup site

Kalman Meth METH at il.ibm.com
Tue Feb 2 14:13:54 CET 2016

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

>> I have the following scenario that I am trying to simulate.
>> I have a volume replicated between clusters A and B, primary on cluster 
>> The volume is attached to and mounted on a VM instance VM1 on cluster 
>> I take a snapshot of VM1.
>> I now imagine that VM1 on cluster A becomes unreachable, so I want to 
>> bring up VM1 on cluster B, and attach to it the replicated volume.
>> I have to make the volume primary on cluster B.
>> As long as the volume is primary on cluster A, I cannot make it primary 
>> cluster B.
>> I want to force the transition of the volume on cluster B from 
>> to primary, without having to perform operations on cluster A.
>> What is the proper sequence of operations / commands to accomplish 
>As in your expected experiment, you will need to cut the communication 
>between the two sites.

>The easiest way to do so is to run "drbdadm disconnect <resource>" on one 

>of the sites; given your requirements, on cluster B.

This changes the state of the volume on cluster B to "OutDated" and I am 
to change the volume to primary. I seem to still be missing something.

I tried to do --force to make the volume primary, but then I was unable to
import it to (OpenStack) cinder and attach it to an instance, since the id 
not recognized.

- Kalman

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