[DRBD-user] Incompatibility versions of DRBD9

[Roland Kammerer]

On Tue, Apr 02, 2019 at 08:36:59PM +0200, kvaps wrote:
> Hello,
> 
> Is there any incompatibility between minor versions of DRBD9 kernel modules?
> Eg. should 9.0.14-1 conflict with the 9.0.16-1 version?

They are compatible. And they are in general. We really try hard to have
them compatible. On connection a min and max version is exchanged and
the nodes agree on a common feature set.

> I want to know for choose right upgrading strategy.
> - Should I stop all storage replicas before upgrade drbd module or it
> can be done online one-by-one?
> - Should I force update on drbd clients (diskless replicas) to not
> harm storage nodes?

The strategy is to move around "stuff" (e.g., live migrate VMs) until a
node is free of primaries. Then you "drbdadm down all", upgrade,
"drbdamd up all". The only other important constraint is that you can
not down such a node if it is the last/only storage provider for a
diskless node. drbdadm would not down such a resource. So you might have
to temporarily increase the redundancy. But I guess you started with a
higher redundancy than 1 anyways.

Regards, rck