AIX

I hardly can think of a scenario where an autoreboot would fix the problem ?
If you have a failing network - reboot doesnt help - neither with failing storage. And even on a failed application - like i.e. a database - a reboot would would only help if someone would have solved the root cause of the failing (that is btw true for auto-failover of a DB - it might not be a good idea at all). If your node fails due to overcommitted memory, the reboot might clear the caches - but the fact that you don't have enough memory or bad tunables would remain, the problem re-occurs soon.
Kind regards
zxmaus

It seems to me like your real problem is adapting to the terminology of HACMP, in this case namely the term "resource group".

Suppose the classical case with no HACMP involved: you have a system where an application runs. The application has some disks holding its data and the data are all in a volume group. Further you have some network adapter (an IP adress) over which the users know they can contact the application.

Now lets abstract from this concept: what do we need to transfer to another system to transfer the task of serving the application? Answer: the volume group with the data, the IP adress the users expect, some start/stop mechanisms for the application - thats it. Exactly this is what is called a resource group. It is a data structure inside the HACMP configuration which binds together exactly these things.

Resource groups always reside on one node of a cluster and can be transferred to another node in case the active node dies. This is what shockneck has tried to explain to you in the active-active configuration: suppose your default would be a node A with some resource group A' operative and a node B with a RG B' operative. If node A dies, RG A' is being transferred to node B which will run both, vice versa, if node B dies.

Yes, "mutual takeover" is just another name for this mechanism. But however you call it, it helps to picture the RGs moving around on the nodes in case of hardware outages.

I hope this helps.

bakunin

Thanks for the answer.

Actually what I did not understand before was what was the value of running 2 instances of the same application on one node during the failover? If the resource group contains the same application on both nodes, why not just make takeover not happen here ? Because from the client point of view, the service still exists while running two same instances on one node may make the node overloaded.

As zxmaus pointed out that two same instances can server different purposes(say, database 1 is used for trading, database 2 for reporting). I think that makes sense. But if two instances serve the same purpose I still don't see the value in it.