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ohasd = Oracle High Availability Services Daemon                 Link to Oracle Clusterware components

Here is the Oracle 11gR2 clusterware startup sequence:

ohasd -> orarootagent -> ora.cssdmonitor : Monitors CSSD and node health (along with the cssdagent). Try to restart the node if the node is unhealthy.

                                    -> ora.ctssd : Cluster Time Synchronization Services Daemon

                                    -> ora.crsd   -> oraagent  -> ora.LISTENER.lsnr

                                                                             -> ora.LISTENER_SCAN.lsnr

                                                                             -> ora.ons

                                                                             -> ora.eons

                                                                             -> ora.asm

                                                                             -> ora.DB.db

                                                         ->orarootagent -> ora.nodename.vip

                                                                                 -> ora.net1.network

                                                                                 -> ora.gns.vip

                                                                                 -> ora.gnsd

                                                                                 -> ora.SCANn.vip

         -> cssdagent -> ora.cssd : Cluster Synchronization Services

         -> oraagent -> ora.mdnsd : Used for DNS lookup
                            -> ora.evmd

                            -> ora.asmd

                            -> ora.gpnpd : Grid Plug and Play = adding a node to the cluster is easier (we need less configuration for the new node)

If a resource is written using blue & bold font => resource owned by root. The other resources are owner by oracle. (all this on UNIX environment)

When a resource is managed by root, we need to run the command crsctl as root or oracle.

Clusterware Resource Status Check

$ crsctl status resource -t
 

--------------------------------------------------------------------------------
NAME                  TARGET  STATE      SERVER            STATE_DETAILS
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.LISTENER.lsnr    

                      ONLINE  ONLINE    tzdev1rac
                      ONLINE  ONLINE    tzdev2rac
ora.asm              

                      OFFLINE OFFLINE   tzdev1rac
                      OFFLINE OFFLINE   tzdev2rac
ora.eons             

                      ONLINE  ONLINE    tzdev1rac
                      ONLINE  ONLINE    tzdev2rac
ora.gsd
                      OFFLINE OFFLINE   tzdev1rac
                      OFFLINE OFFLINE   tzdev2rac
ora.net1.network
                      ONLINE  ONLINE    tzdev1rac
                      ONLINE  ONLINE    tzdev2rac
ora.ons
                      ONLINE  ONLINE    tzdev1rac
                      ONLINE  ONLINE    tzdev2rac
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.LISTENER_SCAN1.lsnr
1                     ONLINE  ONLINE    tzdev1rac
ora.LISTENER_SCAN2.lsnr
1                     ONLINE  ONLINE    tzdev2rac
ora.LISTENER_SCAN3.lsnr
1                     ONLINE  ONLINE    tzdev2rac
ora.oc4j
1                     OFFLINE OFFLINE
ora.scan1.vip
1                     ONLINE  ONLINE    tzdev1rac
ora.scan2.vip
1                     ONLINE  ONLINE    tzdev2rac
ora.scan3.vip
1                     ONLINE  ONLINE    tzdev2rac
ora.trezor.db
1                     ONLINE  ONLINE    tzdev1rac         Open
2                     ONLINE  ONLINE    tzdev2rac
ora.tzdev1rac.vip
1                     ONLINE  ONLINE    tzdev1rac
ora.tzdev2rac.vip
1                     ONLINE  ONLINE    tzdev2rac
 

crsctl start has    -> start all the clusterware services/ resources (including the database server and the listener);
crsctl stop has    -> stop all the clusterware services/ resources (including the database server and the listener);

crsctl check has -> to check if ohasd is running/ stopped

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