Cluster启动顺序大致可以解释为这样的,
INIT也就是init.ohasd (with respawn)，该脚本启动了OHASD进程 (Oracle High Availability Services Daemon). 这个daemon又派生了4个重要进程.
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:
- CRSD – Primary daemon responsible for managing cluster resources.
- CTSSD – Cluster Time Synchronization Services Daemon
- Diskmon
- ACFS (ASM Cluster File System) Drivers
Level 2: OHASD oraagent spawns:
- MDNSD – Used for DNS lookup
- GIPCD – Used for inter-process and inter-node communication
- GPNPD – Grid Plug & Play Profile Daemon
- EVMD – Event Monitor Daemon
- 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
