Tue Nov 26, 2019 12:15 pm
Let me clarify where synchronization priority comes from and why you may (or may not) want to change it.
While replicating a StarWind disk, the device which is used as a source gets greater priority (e.g., First priority). Its copy, in turn, has lower priority (e.g., Second, Third, etc.).These numbers are important only after the synchronization connection fails and is subsequently restored. The device of higher priority is considered synchronized and may lead to data corruption if tuned wrong (with the values you get automatically things work just fine). If you change synchronization priorities, data flow during synchronization may cause data corruption someday. If I were you, I would not change the node synchronization priority. There is a way to do that (and I can share the steps with you in case you might really need it).
Devices with “strange” (neither first nor second) priority appear after you remove the replica on one site and create it again. Say, you have a device on node #1 replicated to node #2 (2-node HA cluster). If you remove the replica from node #1, where it had the First priority, and create the replica again, the device priority will be changed to Third. While you have the synchronization channel up, everything works fine. Once the sync channel is down, the device of higher priority (i.e., First in our case) is supposed to stay active, while the other one will stop accepting iSCSI sessions. This is where the heartbeat links come into play, too, as in absence of sync links they allow services to communicate with one another. After the connection is restored, synchronization starts from there.
The main thing you need to understand about the priorities is that one StarWind node is supposed to have priorities for all devices higher than the partner node:
1 - 2
3 - 4
2 - 3
1 - 2
The above example is totally fine to be used.
If you see anything similar to the below:
1 - 2
2 - 1
3 - 4
3 - 2
then you may want to change the device priority settings, which is done by editing HA device header files. Feel free to get back for additional instruction on how to perform that if needed.