This description is also from the MOS note stated above
Short summary of the startup sequence: INIT spawns init.ohasd (with respawn) which in turn starts the OHASD process (Oracle High Availability Services Daemon). This daemon spawns 4 processes.
Level 1: OHASD Spawns:
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 resources.
cssdmonitor - Monitors CSSD and node health (along wth the cssdagent).
Level 2: OHASD rootagent spawns:
CSDD (ora.cssd) - Cluster Synchronization Services
CRSD(ora.crsd) - Primary daemon responsible for managing cluster resources.
CTSSD(ora.ctssd) - Cluster Time Synchronization Services Daemon
Diskmon(ora.diskmon)
ACFS (ASM Cluster File System) Drivers
Level 2: OHASD oraagent spawns:
MDNSD(ora.mdnsd) - Used for DNS lookup
GIPCD(ora.gipcd) - Used for inter-process and inter-node communication
GPNPD(ora.gpnpd) - Grid Plug & Play Profile Daemon
EVMD(ora.evmd) - Event Monitor Daemon
ASM(ora.asm) - Resource for monitoring ASM instances
Level 3: CRSD spawns:
orarootagent - Agent responsible for managing all root owned crsd resources.
oraagent - Agent responsible for managing all oracle owned crsd resources.
Level 4: CRSD rootagent spawns:
Network resource - To monitor the public network
SCAN VIP(s) - Single Client Access Name Virtual IPs
Node VIPs - One per node
ACFS Registery - For mounting ASM Cluster File System
GNS VIP (optional) - VIP for GNS
Level 4: CRSD oraagent spawns:
ASM Resouce - ASM Instance(s) resource
Diskgroup - Used for managing/monitoring ASM diskgroups.
DB Resource - Used for monitoring and managing the DB and instances
SCAN Listener - Listener for single client access name, listening on SCAN VIP
Listener - Node listener listening on the Node VIP
Services - Used for monitoring and managing services
ONS - Oracle Notification Service
eONS - Enhanced Oracle Notification Service
GSD - For 9i backward compatibility
GNS (optional) - Grid Naming Service - Performs name resolution
Short summary of the startup sequence: INIT spawns init.ohasd (with respawn) which in turn starts the OHASD process (Oracle High Availability Services Daemon). This daemon spawns 4 processes.
Level 1: OHASD Spawns:
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 resources.
cssdmonitor - Monitors CSSD and node health (along wth the cssdagent).
Level 2: OHASD rootagent spawns:
CSDD (ora.cssd) - Cluster Synchronization Services
CRSD(ora.crsd) - Primary daemon responsible for managing cluster resources.
CTSSD(ora.ctssd) - Cluster Time Synchronization Services Daemon
Diskmon(ora.diskmon)
ACFS (ASM Cluster File System) Drivers
Level 2: OHASD oraagent spawns:
MDNSD(ora.mdnsd) - Used for DNS lookup
GIPCD(ora.gipcd) - Used for inter-process and inter-node communication
GPNPD(ora.gpnpd) - Grid Plug & Play Profile Daemon
EVMD(ora.evmd) - Event Monitor Daemon
ASM(ora.asm) - Resource for monitoring ASM instances
Level 3: CRSD spawns:
orarootagent - Agent responsible for managing all root owned crsd resources.
oraagent - Agent responsible for managing all oracle owned crsd resources.
Level 4: CRSD rootagent spawns:
Network resource - To monitor the public network
SCAN VIP(s) - Single Client Access Name Virtual IPs
Node VIPs - One per node
ACFS Registery - For mounting ASM Cluster File System
GNS VIP (optional) - VIP for GNS
Level 4: CRSD oraagent spawns:
ASM Resouce - ASM Instance(s) resource
Diskgroup - Used for managing/monitoring ASM diskgroups.
DB Resource - Used for monitoring and managing the DB and instances
SCAN Listener - Listener for single client access name, listening on SCAN VIP
Listener - Node listener listening on the Node VIP
Services - Used for monitoring and managing services
ONS - Oracle Notification Service
eONS - Enhanced Oracle Notification Service
GSD - For 9i backward compatibility
GNS (optional) - Grid Naming Service - Performs name resolution
