This figure depicts the startup process for Oracle Clusterware. The INIT process starts ohasd, which, in turn, starts the oraagent, orarootagent, and cssdagent. These processes then carry out the following steps:
1.oraagent ->
mdnsd
evmd
Oracle ASM
gpnpd
gipcd (Grid IPC daemon)
2.orarootagent ->
OSYSMOND (which, on some nodes, starts OLOGGERD, not shown in the graphic)
ctssd
the CSSD Monitor
diskmon (Disk Monitor daemon)
crsd ->
2.1.oraagent -> Oracle Notification Service (ONS and eONS), an Oracle ASM instance (which communicates with Oracle ASM started by the oraagent that ohasd started), the database instance, the listeners, and the SCAN listeners
2.2.orarootagent -> gnsd, the VIPs, the SCAN VIP, and the network resources. Additionally, the orarootagent starts the Oracle ADVM volume, Oracle ACFS, the NFS service, the high-availability NFS service, and the high-availability VIP.
3.cssdagent ->
Cluster Synchronization Service (ocssd)
https://docs.oracle.com/en/database/oracle/oracle-database/18/cwadd/img_text/cwadd006_ha_stack.html
