[ClusterLabs Developers] migrate-to and migrate-from for moving Master/Slave roles ?

[Andrei Borzenkov]

On Fri, Dec 4, 2015 at 4:11 PM, Jehan-Guillaume de Rorthais
<jgdr at dalibo.com> wrote:

>
> But I fail to understand how I could distinguish, even from notifications, a
> failing scenario from a move/switchover one.
>

On demote fetch current log position and store it in cluster
attribute. On promote fetch previous master position, wait until
current instance caught up and delete attribute. If attribute is not
present on promote, master was down so do not wait and proceed.

If you set transient attribute, cluster will forget about previous
master on restart. If you set persistent attribute, it will allow you
to ensure no data loss has (automatically) occurred even on cluster
restart.

Where do you envision problems here?