Hello,
in my opinion it's not a quite good idea to start one package from the other (if i understood you start application server from central instance package). We have a configuration here, where we start db and ci in one package and have up to three application servers always trying to start up in parallel. We simply check if the dbci-package is running in the customer_defined_run_commands of the app-packages in a while loop (10 tries, 20 seconds sleep), and if this succeeds the package can go on to start it's sap-application-server. So it's YOU who checks for db and ci and not the sap-script, which should not end up in a deadlock situation.
The second question is not quite clear to me. The only situation where the db-package is going down before the others should be a failure. If you are bringing the cluster down manually, it's only a question of discipline. Ok, it's possible that you have a failure of the db-package alone and then you are in a mess, i see (should be very rare condition). A possible solution is, that you are using a seperat NFS-package for this. The only problem now is, that mostly the NFS-package is the first to fail if there are any problems, but it should also be the first one that come up on the other node.
As i said, we only have dbci and app seperated and each one has all necessary binaries in the package, giving you much overhead but good stability in cluster operations.
Hope i really understood your problem and giving some hints here.
Heinz
