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Note: All the posts are based on practical approach avoiding lengthy theory. All have been tested on some development servers. Please don’t test any post on production servers until you are sure.

Monday, December 06, 2010

Administring Clusterware (10gR2)

Oracle Clusterware is the cross platform cluster software required to run the Real Application Clusters (RAC) option for Oracle Database. It provides the basic clustering services at the operating system level that enable Oracle software to run in clustering mode.

Oracle Clusterware is run by Cluster Ready Services (CRS) using two key components. They are Oracle Cluster Registry (OCR), which records and maintains the cluster and node membership information. The other component is voting disk, which acts a tiebreaker during communication failures.
Consistent heartbeat information from all the nodes is sent to voting disk when the cluster is running. CRS service has four components namely OPROCd, CRS Daemon (crsd), Oracle Cluster Synchronization Service Daemon (OCSSD) and Event Volume Manager Daemon (evmd) and each handles a variety of functions. Failure or death of the CRS daemon can cause the node failure and it automatically reboots the nodes to avoid the data corruption because of the possible communication failure between the nodes. The CRS daemon runs as the super user ‘root’ in the UNIX platforms and runs as a service in the windows platforms.
D:\oracle\product\10.2.0\crs\BIN>crs_stat -t (to check out resources status)
Name           Type           Target    State     Host
ora....E1.inst application    ONLINE    ONLINE    db1
ora....E2.inst application    ONLINE    ONLINE    db2
ora.HOME.db    application    ONLINE    ONLINE    db2
ora....SM1.asm application    ONLINE    ONLINE    db1
ora....11.lsnr application    ONLINE    ONLINE    db1
ora....b11.gsd application    ONLINE    ONLINE    db1
ora....b11.ons application    ONLINE    ONLINE    db1 application    ONLINE    ONLINE    db1
ora....SM2.asm application    ONLINE    ONLINE    db2
ora....12.lsnr application    ONLINE    ONLINE    db2
ora....b12.gsd application    ONLINE    ONLINE    db2
ora....b12.ons application    ONLINE    ONLINE    db2 application    ONLINE    ONLINE    db2

D:\oracle\product\10.2.0\crs\BIN>crs_stat -v
RESTART_COUNT=0   (how many times an application resource was restarted on a node)
FAILURE_COUNT=0  (failure count of a resource within the FAILURE_INTERVAL)

D:\oracle\product\10.2.0\crs\BIN> crs_start  (attempts to start the specified registered applications)
D:\oracle\product\10.2.0\crs\BIN> crs_stop  (stops specified registered applications) 
D:\oracle\product\10.2.0\crs\BIN> crs_stop -all
D:\oracle\product\10.2.0\crs\BIN> crs_unregister (removes the registration information of Oracle Clusterware resources

D:\oracle\product\10.2.0\crs\BIN>crsctl check crs
CSS appears healthy
CRS appears healthy
EVM appears healthy

Start Oracle Clusterware
#crsctl start crs
Stop Oracle Clusterware
#crsctl stop crs
Enable Oracle Clusterware
#crsctl enable crs
It enables automatic startup of Clusterware daemons

Disable Oracle Clusterware
#crsctl disable crs
It disables automatic startup of Clusterware daemons. This is useful when you are performing some operations like OS patching and does not want clusterware to start the daemons automatically.
Add Voting disk
#crsctl add css votedisk path
Remove Voting disk
#crsctl delete css votedisk path
You can also see particular daemon status
C:\Documents and Settings\inam>crsctl check cssd
CSS appears healthy 

C:\Documents and Settings\inam>crsctl check crsd
CRS appears healthy

C:\Documents and Settings\inam>crsctl check evmd
EVM appears healthy

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