troubleshoot hang application

hi,

if an application hangs and it is part of an service group,how i troubleshoot things?

first should i stop the service group hagrp -offline?if this not works then should i try to stop each resource hares -offline?if this not wotks then i kill -9 every process of this application.

should i take out the floating ip?and unmount if trhe above not work?

then i start everything with hagrp -online?

normally the application resides on SAN luns not on local disk from server.right?

in this case if there are some issues with dg,volumes or plexes and i freeze this group,then the application could hang.right?

tnx a lot.