Oracle Clusterware Startup Sequence - RAC Startup Sequence (OHASD, CSSD, GPNPD & CRSD) - Oracle RAC

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Oracle Clusterware Startup Sequence - RAC Startup Sequence (OHASD, CSSD, GPNPD & CRSD) - Oracle RAC:
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Interview Question?
ohasd process to start what it will look?
cssd to start what it will look?
crsd to start what it will look?
gpnp process to start what it will look?

Brief me about clusterware start-up sequence?

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(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


#RAC #RACDaemons #OracleClustearwareStartupSequence #exadata #oracle #oracledatabase #oracledba #database #databaseperformanceIssue


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