Making and backing up a snapshot of a JFS2

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You can make a snapshot of a mounted JFS2 that establishes a consistent block-level image of the file system at a point in time.

The information in this how-to scenario was tested using specific versions of AIX. The results you obtain might vary significantly depending on your version and level of AIX.

The snapshot image remains stable even as the file system that was used to create the snapshot, called the snappedFS, continues to change. The snapshot retains the same security permissions as the snappedFS had when the snapshot was made.

In the following scenario, you create a snapshot and back up the snapshot to removable media without unmounting or quiescing the file system, all with one command: backsnap. You can also use the snapshot for other purposes, such as accessing the files or directories as they existed when the snapshot was taken. You can do the various snapshot procedures by using SMIT or the backsnap and snapshot commands.

To create a snapshot of the /home/abc/test file system and back it up (by name) to the tape device /dev/rmt0, use the following command:

backsnap -m /tmp/snapshot -s size=16M -i f/dev/rmt0 /home/abc/test

This command creates a logical volume of 16 megabytes for the snapshot of the JFS2 file system (/home/abc/test). The snapshot is mounted on /tmp/snapshot and then a backup by name of the snapshot is made to the tape device. After the backup completes, the snapshot remains mounted. Use the -R flag with the backsnap command if you want the snapshot removed when the backup completes.