Use volume append mode to create WORM appendable files

Contributors

Starting with ONTAP 9.3, you can use the SnapLock volume append mode (VAM) feature to create WORM appendable files by default. A WORM appendable file retains data written incrementally, like log entries. Data is appended to the file in 256 KB chunks. As each chunk is written, the previous chunk becomes WORM-protected. You cannot delete the file until the retention period has elapsed.

What you’ll need
  • The WORM appendable file must reside on a SnapLock volume.

  • The SnapLock volume must be unmounted and empty of Snapshot copies and user-created files.

About this task

Data does not have to be written sequentially to the active 256 KB chunk. When data is written to byte n×256KB+1 of the file, the previous 256 KB segment becomes WORM-protected.

If you specify an autocommit period for the volume, WORM appendable files that are not modified for a period greater than the autocommit period are committed to WORM.

Note

VAM is not supported on SnapLock audit log volumes.

Steps
  1. Enable VAM:

    volume snaplock modify -vserver SVM_name -volume volume_name -is-volume-append-mode-enabled true|false

    For a complete list of options, see the man page for the command.

    The following command enables VAM on volume vol1 of SVMvs1:

    cluster1::>volume snaplock modify -vserver vs1 -volume vol1 -is-volume-append-mode-enabled true
  2. Use a suitable command or program to create files with write permissions.

    The files are WORM appendable by default.