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RAC Administration

Cluster ware provide the services to manage cluster.

  • Cluster Management
  • Node Monitoring
  • Event Services
  • CTS (Cluster Time Syn)
  • Network Management
  • High Availability

Shared Disk + Load Balancing


Active / Active

Active / Passive

Shared drive   OCR , Voting Disk

Voting Disk – Records “heart – beat” information all nodes with cssd process.

Can Multiplexed, Mirrored

Min 3 Copies recommended.

Supports up to 5 copies and max 15 copies

Voting disk can configure on oracle asm or shared storage,if you provide single voting disk you have to configure External Redundancy.

OCR – crsd process is reading and writing to OCR files.

            Oracle cluster registry to store information and manage cluster components like rac databases,listerers,virtual IP addresses and services of any applications.

What stored in OCR

  • Node membership information what are part of clusters.
  • Software active version.
  • The location of the 11g voting disk
  • Server pools
  • Status of cluster resources such rac databases, listerners, instances and services.
    1. Server up / down
    2. Network up / down
    3. Database up /down
    4. Instance up/down
    5. Listener up / down
  • ASM instance , disk groups etc…
  • Configuration of cluster resources such rac databases, listerners, instances and services
    1. Dependencies
    2. Management policy ( automatic / manual )
    3. Reties
  • Information about OCR backups
  • Database services characteristics


b)TAF policy

c)Load balancing goal etc.

Oracle cluster processes

                CRS –      Cluster Ready Services

                CSS –      Cluster Synchronization Service

                EVM –    Event Management

                ONS –    Oracle Notification Service

Oracle cluster ware consists of two separates stacks

Upper stack        –              CRS (Cluster Ready Services) – crsd daemon

Lower stack        –              Oracle High availability components – ohasd daemon


  • Used for cache fusion & cluster messaging. Private network using that can access only nodes in the cluster. Gv$cluster_interconnects

CRSCTL – Cluster related can handle

SRVCTL – Database related

For listener -> GRID_HOME/bin/srvctl

For database -> ORACLE_HOME/bin/srvctl

#crsctl enable crs

#crsctl disable crs

#crsctl check crs

#crsctl check cluster


#ps –ef|grep d.bin     ->> services of clusterware

#crsctl stop | Start crs (only 1 node it will stop)

To verify Grid error logs in below path

grid$ cd /u01/app/grid/logs/

grid$ps –ef|grep tnslsnr

Note:- In oracle 10g listener will run with oracle user, Oracle 11g now with grid user.

Oracle$srvctl stop instance –I yahoo1 –d yahoo

Grid$srvctl stop asm

Grid$srvctl stop listener


#cat /etc/oracle/ocr.loc -----finding the location

#crsctl query css votedisk


# ocrconfig -showbackup   -------Automatically takes backup for every 4 hours for voting disk, It is physical backups

# ocrconfig –manualbackup

#ocrconfig –export /root/ocrlogic.bkp

# ocrcheck -local

#cat /etc/oracle/ocr.loc ---to check the locations

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