Understanding how the clusterware startup occurs is critical to the diagnosis and resolution of Oracle RAC problems.
In Unix and Linux operating systems, there is a master daemon process named
INIT that functions to start up additional system background processes. The
INIT process first spawns the
init.ohasd process, which in turn starts up the Oracle High Availability Services Daemon (OHASD). In turn, the OHASD daemon then spawns additional Clusterware processes at each startup level as shown next:
Cssdagent:Agent responsible for spawning CSSD
Orarootagent:Agent responsible for managing all root-owned ohasd resources
Oraagent:Agent responsible for managing all Oracle-owned ohasd ...