content_image/1013340.jpg
After you release the unused space, it becomes marked as Pending  in the ProtecTIER repository. The ProtecTIER repository then automatically uses internal processes to optimize the available space for future backups: 

GLYPH<SM590000> Internal Deleter processes reduce the Pending space and, in the process, create Fragmented space. 

GLYPH<SM590000> Internal Defragger processes then reduce the Fragmented space. 

In the Capacity section of the ProtecTIER GUI (Figure 2-3), the pie chart at the right side shows the nominal data, and you can see the pending space. In this example, the pending space is 16.9 terabytes (TB). 

<img src='content_image/1013340.jpg'>

As a result of the delete operation, some fragmented space can occur, as shown in the pie chart on the left in Figure 2-3. Further ProtecTIER internal housekeeping eliminates that space. The newly reworked repository is perfectly aligned to your next incoming backup. 

## 2.5.6 ProtecTIER repository usage 

From a technical standpoint, there is no problem with having a ProtecTIER repository that is 100% used (although from a usability standpoint it is not a good practice to permit a repository to get 100% full). After you reach a steady state where daily housekeeping frees up enough space to enable daily backups, a high usage is possible. 

In reality, data tends to grow, so sooner or later you can face changed requirements for your ProtecTIER repository size. You should configure an automated message that informs you when the repository usage crosses a specified threshold value. Depending on the time you need to prepare a capacity upgrade of the ProtecTIER back-end storage, values greater than 80% or 90% can be selected to provide ample time for preparation. 

