o2info

The o2info command is part of the OCFS2 (Oracle Cluster File System 2) tools suite and is used to display detailed information about a mounted OCFS2 file system. It provides insights into various aspects of the file system, including superblock information, cluster layout, and other metadata details.

Purpose

• Inspect OCFS2 File System Details: o2info provides detailed information about the structure and metadata of an OCFS2 file system, which is useful for both debugging and monitoring purposes.

• Superblock Inspection: It allows administrators to inspect the OCFS2 superblock, a key component that contains the file system's metadata.

• Cluster Information: Shows information about the cluster nodes involved with the OCFS2 file system, which is crucial in a clustered environment.

Basic Syntax

o2info [OPTIONS] <MOUNT_POINT>

• <MOUNT_POINT>: The path where the OCFS2 file system is mounted.

Common Options

• -s or --superblock: Display detailed information about the superblock of the OCFS2 file system.

  Example:

  o2info --superblock /mnt/ocfs2

• -C or --cluster: Display detailed cluster layout and node information for the OCFS2 file system.

  Example:

  o2info --cluster /mnt/ocfs2

• -h or --help: Display help information about the command.

  Example:

  o2info --help

• -V or --version: Display the version of o2info.

  Example:

  o2info --version

Example Usage

1. Viewing Superblock Information

   To view detailed superblock information for an OCFS2 file system mounted at /mnt/ocfs2:

   o2info --superblock /mnt/ocfs2

   This will display important superblock data, such as block size, cluster size, UUID, and more.

2. Viewing Cluster Layout and Node Information

   To display the cluster information for an OCFS2 file system mounted at /mnt/ocfs2:

   o2info --cluster /mnt/ocfs2

   This will show the nodes participating in the OCFS2 cluster, their roles, and the current status.

Example Output

When running o2info to view superblock information, you may see output like this:

Superblock Information
-----------------------
Block Size: 4096
Cluster Size: 65536
Volume UUID: 12345678-90ab-cdef-1234-567890abcdef
Volume Label: MyClusterFS
Node Slots: 8

For cluster information, the output may look like this:

Cluster Information
--------------------
Cluster Name: ocfs2_cluster
Node Count: 3
Node 1: Online
Node 2: Online
Node 3: Online

Best Practices

• Monitor File System Health: Use o2info --superblock regularly to check the health and consistency of the superblock on your OCFS2 file systems.

• Cluster Node Management: Check the cluster layout and node information using o2info --cluster to ensure all nodes in the cluster are communicating and functioning properly.

• Troubleshooting: Use the detailed output from o2info to assist in diagnosing file system or cluster-related issues.

Conclusion

o2info is a valuable tool for administrators managing OCFS2 file systems in clustered environments. It provides critical information about the file system's superblock and cluster configuration, aiding in file system monitoring, debugging, and management.