Tape Rehydratation

The tape rehydration process is design to optimize the space on a tape.

When files are deleted from a tape, they are not completely erased. To completely erase the files, a rehydration task is required. This is done to enhance performance and improve the end-user experience.

In these situations, Nodeum does not delete or modify the files stored on the tapes. For deletions, the entry in the catalog is removed, and for updates, the new version is written while the index pointer is changed. The files are never physically deleted from the tape.

As a consequence, when a certain number of file deletions or updates occur, the ratio between the available free space and the actual consumed space on these tapes becomes imbalanced.

The tape rehydration workflow is available in the Maintenance Task workflow.

Go in the menu Storage Services/Tape/Maintenance

Complete the form:

1. Define the task name and comments

2. Select the Action: Rehydration

3. Choose one or several tapes

4. Schedule the Task

5. Define Other Options

Priority

You can specify the priority of the task to be run.

If multiple tasks are running simultaneously, tasks with higher priority will be run first.

You can choose Priority 1 until Max. 10.

The Higher Priority is 10, thus if you consider that this task is the higher priority, you must choose 10.

Tape Capacity Usage

This value is in % The workflow will be activated for the tape when it reaches this minimum capacity threshold.

Capacity volume that need to be cleaned

This value is in % The workflow will be activated for the tape when it reaches this capacity space that can be reclaimed on the tape.

This two last options are very important to be set to get the space reclamation you are looking for.