Database Reference
In-Depth Information
Cluster Time Synchronization Service (CTSS): A new daemon process introduced with 11gR2, which handles the
time synchronization among all the nodes in the cluster. You can use the OS's Network Time Protocol (NTP) service to
synchronize the time. Or, if you disable NTP service, CTSS will provide the time synchronization service. This service
runs as the
octssd.bin
process on Linux/Unix or
octssd.exe
on Windows.
Event Management (EVM): This background process publishes events to all the members of the cluster. On
Linux/Unix, the process name is
evmd.bin
, and on Windows, it is
evmd.exe
.
ONS: This is the publish and subscribe service that communicates Fast Application Notification (FAN) events.
This service is the
ons
process on Linux/Unix and
ons.exe on Windows.
Oracle ASM: Provides the volume manager and shared storage management for Oracle Clusterware and Oracle
Database.
Clusterware agent processes: Oracle Agent (
oraagent
) and Oracle Root Agent (
orarootagent
). The
oraagent
agent is responsible for managing all Oracle-owned
ohasd
resources. The
orarootagent
is the agent responsible for
managing all root-owned
ohasd
resources.
Clusterware Startup Sequence
Oracle Clusterware is started up automatically when the RAC node starts. This startup process runs through several
levels. Figure
2-3
shows the multiple-level startup sequences to start the entire Grid Infrastructure stack plus the
resources that Clusterware manages.
Level 0
Level 1
Level 2
Level 3
Level 4
Network
sources
cssdmonitor
ASM
SCANIP
Node VIP
mDNSD
CRSD
orarootagent
ACF Registry
OHASD
oraagent
GIPCD
GNSVIP
EVMD
ASM
instance
GPNPD
Diskgroup
CRSD
DB Resource
CTSSD
SCAN
Listener
OHASD
oraclerootagent
Diskmon
Listener
CRSD
oraagent
Services
eONS
cssdagent
CSSD
ONS
Process on the High Availability Stack
GPNPD
GNS
CTSSD
Process on the Cluster Ready Service Stack
GSD
Services
Resource managed by Cluster Ready Service
Figure 2-3.
Startup sequence of 12cR1 Clusterware processes
