Clusterware :: Manage Active Passive Cluster On SLES10 SP4

I have to manage an active passive cluster on SLES10 SP4. Oracle 10.2.0.4. All oracle binaries are on a DRBD Device on mountpoint /oradata. This mountpoint includes the binaries and all datafiles.

I havent installed these systems. At one stage on node died and got reinstalled by a system administrator. After a switch from the running node to the standby node, the cluster is not starting.

Jan 3 14:36:01 a logger: Cluster Ready Services waiting on dependencies. Diagnostics in /tmp/crsctl.6114.
Jan 3 14:36:14 a logger: Waiting for Oracle CSS service to be available before starting
Jan 3 14:36:14 a logger: ASM instance +ASM. Wait 2.

After issuing $ORACLE_HOME/bin/localconfig add the cluster is starting, the asm instance is coming up, and also the database instance is starting.

Shortly after that the db instance dies. Alert log is showing something like recursive sql error. Looks like writing to the datafiles is not working. In asmcmd the diskgroups are showing DISMOUNTED (show MOUNTED before)

so what to do ?
a) Why is it necessary to issue "localconfig add" to make the cluster starting ?
b) What could be a reason for not being able to write to the database ?
c) How to install an active/passive cluster ?
c1) Install OS on both nodes
c2) Install oracle binaries
c2.1) on both nodes in the local files system and do the mapping to the drbd afterwards?
c2.2) only on one node and just switch the mountpoint ?