Clever donor election
It would be great to have a smart mechanism to elect the donor.
For example if you have 3 nodes (A, B and C) and you stop B and C.
If you start the nodes again (one by one), if gcache is large enough, the cluster will promote A as donor and perform IST. Then when C is back online, the cluster may elect B as donor for C and then IST won't be possible and SST will be started even if IST would have been possible if A was chosen as donor.
It would be great that the cluster checks if IST is possible from a donor before electing one.
Blueprint information
- Status:
- Not started
- Approver:
- None
- Priority:
- Undefined
- Drafter:
- None
- Direction:
- Needs approval
- Assignee:
- None
- Definition:
- New
- Series goal:
- None
- Implementation:
-
Unknown
- Milestone target:
-
future-5.5
- Started by
- Completed by
Related branches
Related bugs
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1 )Currently the way I see it,
there are 3 ways a donor is chosen
a) The one who sends the request himself wants to be the
donor. - used by RSU
b) There is already a donor chosen by name. - wsrep_sst_donor (http://
c) Otherwise,
for (idx = 0; idx < group->num; idx++) {
gcs_node_t* node = &group->nodes[idx];
if (status == node->status &&
strcmp (node->name, GCS_ARBITRATOR_
return idx;
}
2)
One more thing, wsrep_sst_donor is a dynamic variable.
3)
The simplest way is to try IST with all nodes (or a pre-determined list of nodes) and only then SST.
4) Related bug https:/
5) Another related bug https:/
I think http://
