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11g Grid Infrastructure (RAC): CRS Startup Sequence

 

This is about to understand the startup sequence of Grid Infrastructure daemons and its resources in 11gR2 RAC.

 

In 11g RAC aka Grid Infrastructure we all know there are additional background daemons and agents, and the Oracle documentation is not so clear nor the other blog.

 

For example:- I have found below diagram from metalink which is very confusing.

 

 

Whilst reading the book “http://www.amazon.com/Pro-Oracle-Database-11g-Linux/dp/1430229586” found excellent diagram representing the same but very understandable manner. (at least for me)

 

image

Without much hassle or discussion with bottom to top approach, I understand now,

OHASD Phase:-

  • OHASD (Oracle High Availability Server Daemon) starts Firsts and it will start

OHASD Agent Phase:-

  • OHASD Agent starts and in turn this will start
gipcd Grid interprocess communication daemon, used for monitoring cluster interconnect
mdnsd Multicast DNS service It resolves DNS requests on behalf of GNS
gns The Grid Naming Service (GNS), a gateway between DNS and mdnsd, resolves DNS requests
gpnpd Grid Plug and Play Daemon, Basically a profile similar like OCR contents stored in XML format in $GI_HOME/gpnp/profiles/<peer> etc., this is where used by OCSSD also to read the ASM disk locations to start up with out having ASM to be up, moreover this also provides the plug and play profile where this can be distributed across nodes to cluster
evmd/

evmlogger

 Evm service will be provided by evmd daemon, which is a information about events happening in cluster, stop node,start node, start instance etc.
  • cssdagent (cluster synchronization service agent), in turn starts
ocssd Cluster synchronization service daemon which manages node membership in the cluster

If cssd found that ocssd is down, it will reboot the node to protect the data integrity.

 

  • cssdmonitor (cluster synchronization service monitor), replaces oprocd and provides I/O fencing

 

  • OHASD orarootagent starts and in turn starts
crsd.bin Cluster ready services, which manages high availability of cluster resources , like stopping , starting, failing over etc.
diskmon.bin disk monitor (diskdaemon monitor) provides I/O fencing for exadata storage
octssd.bin Cluster synchronization time services , provides Network time protocol services but manages its own rather depending on OS

CRSD Agent Phase:- crsd.bin starts two more agents

crsd orarootagent(Oracle root agent) starts and in turn this will start

gns Grid interprocess communication daemon, used for monitoring cluster interconnect
gns vip Multicast DNS service It resolves DNS requests on behalf of GNS
Network Monitor the additional networks to provide HAIP to cluster interconnects
Scan vip Monitor the scan vip, if found fail or unreachable failed to other node
Node vip Monitor the node vip, if found fail or unreachable failed to other node

crsd oraagent(Oracle Agent) starts and in turn it will start (the same functionality in 11gr1 and 10g managed by racgmain and racgimon background process) which is now managed by crs Oracle agent itself.

·

ASM & disk groups Start & monitor local asm instance
ONS FAN feature, provides notification to interested client
eONS FAN feature, provides notification to interested client
SCAN Listener Start & Monitor scan listener
Node Listener Start & monitor the node listener (rdbms?)

Hope this helps, comments & suggestions are most welcome.

-Thanks

Geek DBA

September 28th, 2012 | Tags: , , , | Category: GridInfrastructure

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