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

Digimer lists at alteeve.ca
Mon Feb 1 21:32:18 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.

On 01/02/16 09:37 AM, Kalman Meth wrote:
> I have the following scenario that I am trying to simulate.
> I have a volume replicated between clusters A and B, primary on cluster A.
> The volume is attached to and mounted on a VM instance VM1 on cluster A.
> 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
> on cluster B.
> I want to force the transition of the volume on cluster B from secondary
> to primary, without having to perform operations on cluster A.
> What is the proper sequence of operations / commands to accomplish this?
> Thank you,
> - Kalman
> Kalman Z. Meth, PhD.
> Cloud Platforms
> IBM Haifa Research Lab
> Haifa University Campus, Mount Carmel,
> Haifa, 31905, Israel
> e-mail: meth at il.ibm.com, Tel: +972 4 829 6341, Fax: +972 4 829 6114

Fencing handles this.

Node 2 loses contact with node 1, times out, asks the cluster to fence
node 1. When fencing succeeds, Node 2 knows the state of node 1 (off)
and can safely promote itself without causing a split-brain and recovery
can proceed.

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access to education?

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