Mastering Oracle RAC with CRSCTL commands

Mastering Oracle Clusterware Administration: Essential Commands & Best Practices

Oracle Clusterware is a key component for managing cluster environments, ensuring high availability and resource management for Oracle databases. Below are essential commands for managing Oracle Clusterware effectively.

What is crsctl?

crsctl (Cluster Ready Services Control) is a command-line utility provided by Oracle to manage Oracle Clusterware. It allows administrators to start, stop, check, and configure various aspects of cluster services. With crsctl, DBAs can control cluster resources, manage voting disks, check the status of Oracle High Availability Services, and ensure the proper functioning of Oracle RAC environments.

Starting and Stopping Oracle Clusterware

On Local Node

Stop Clusterware:
```
crsctl stop cluster
```
Start Clusterware:
```
crsctl start cluster
```

On RAC Standalone/Oracle Restart

Stop Cluster:
```
crsctl stop has
```
Start Cluster:
```
crsctl start has
```

On All Nodes or All Hub Nodes

Start Clusterware:
```
crsctl start cluster
```

Enabling or Disabling Automatic Startup

Enable automatic startup:
```
crsctl enable crsctl
```
Disable automatic startup:
```
crsctl disable crsctl
```

Checking Clusterware Status

Check CRS status on a local node:
```
crsctl check crsctl
```
View Oracle High Availability Stack:
```
crsctl stat res -init -t
```
Query Cluster Extended Status:
```
crsctl get cluster extended
```
Query Cluster Sites:
```
crsctl query cluster site -all
```
Confirm CTSSD is active after installation:
```
crsctl check ctss
```

Managing Cluster Nodes

Delete a node from the cluster:
```
crsctl delete node -n hostname
```

Configuring Oracle High Availability Services

Display automatic startup configuration:
```
crsctl config crs
```

Checking Cluster Status Across Nodes

Check cluster status from all nodes:
```
crsctl check cluster -all
```

Determining Storage Locations

Determine the location of the Voting Disk:
```
crsctl query css votedisk
```
Determine the location of the Oracle Cluster Registry (OCR):
```
ocrcheck -config
```

Checking Clusterware Version

Verify the currently running version:
```
crsctl query crs activeversion
```
Check the software version on a single node:
```
crsctl query crs softwareversion [hostname]
```

Stopping and Starting Clusterware Across Nodes

Stop Clusterware on all nodes (as root):
```
crsctl stop cluster -all
```
Start Clusterware stack on one node in exclusive mode:
```
crsctl start crs -excl -nocrs
```

Managing Voting Disks

Add a Voting Disk to non-ASM storage:

crsctl add css votedisk <path_to_new_voting_disk>

Delete a Voting Disk from non-ASM storage:

crsctl delete css votedisk <path_to_old_voting_disk>

Move a Voting Disk to an ASM Disk Group:
```
crsctl replace votedisk +asm_disk_group
```

Migrate Voting Disks between ASM and non-ASM storage:

crsctl replace votedisk {+asm_disk_group | path_to_voting_disk}

Monitoring and Logging

Monitor Clusterware-managed resource utility:
```
crsctl query calog
```
Query maximum space allocated to cluster resource activity logs:
```
crsctl get calog maxsize
```

By using these commands, Oracle Database Administrators can effectively manage and monitor Oracle Clusterware environments, ensuring high availability and efficient resource management.

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