Clusterware Stack Management and Troubleshooting - Expert Oracle RAC 12c - page 34

Level 0: The OS automatically starts Clusterware through the OS's init process. The init process spawns only
one init.ohasd , which in turn starts the OHASD process. This is configured in the /etc/inittab file:

$cat /etc/inittab|grep init.d | grep -v grep
h1:35:respawn:/etc/init.d/init.ohasd run >/dev/null 2>&1 </dev/null
Oracle Linux 6.x and Red Hat Linux 6.x have deprecated inittab. init.ohasd is configured in startup
in /etc/init/oracle-ohasd.conf:
$ cat /etc/init/oracle-ohasd.conf
......

start on runlevel [35]
stop on runlevel [!35]
respawn
exec /etc/init.d/init.ohasd run >/dev/null 2>&1 </dev/null
This starts up "init.ohasd run", which in turn starts up the ohasd.bin background process:
$ ps -ef | grep ohasd | grep -v grep
root 4056 1 1 Feb19 ? 01:54:34 /u01/app/12.1.0/grid/bin/ohasd.bin reboot
root 22715 1 0 Feb19 ? 00:00:00 /bin/sh /etc/init.d/init.ohasd run

Once OHASD is started on Level 0, OHASD is responsible for starting the rest of the Clusterware and the resources
that Clusterware manages directly or indirectly through Levels 1-4. The following discussion shows the four levels of
cluster startup sequence shown in the preceding Figure 2-3 .

Level 1: OHASD directly spawns four agent processes:
•

cssdmonitor : CSS Monitor

•

OHASD orarootagent : High Availability Service stack Oracle root agent

•

OHASD oraagent : High Availability Service stack Oracle agent

•

cssdagent : CSS Agent

Level 2: On this level, OHASD oraagent spawns five processes:

mDNSD : mDNS daemon process •

GIPCD : Grid Interprocess Communication •

GPnPD : GPnP profile daemon •

EVMD : Event Monitor daemon

•

ASM : Resource for monitoring ASM instances
Then, OHASD oraclerootagent spawns the following processes:

•

CRSD : CRS daemon •

CTSSD : CTSS daemon •

Diskmon : Disk Monitor daemon (Exadata Storage Server storage)

•

ACFS : (ASM Cluster File System) Drivers
Next, the cssdagent starts the CSSD (CSS daemon) process.

•