Why OST Files Are Not Included In The Backup?


In this article, you'll find detailed instructions on what to do, when you want to back up .OST mail files. Xopero ONE uses VSS (Microsoft Volume Shadow Copy Service) for backup operations. Some files are excluded from snapshots (e.g. deleted, temporary, paging or OST files). The FilesNotToSnapshot registry key in Windows Registry is responsible for the exclusion (more about it here). The system will skip the excluded files when taking the snapshot, so these files will not be included in the backup.


The files that are excluded from VSS can be found in the FilesNotToSnapshot registry key. You can include these files in VSS by removing specific values from the registry key.

  1. Start Registry Editor by executing regedit from any command-line area in Windows. E.g. In the search box on the taskbar, type regedit, then select Registry Editor (Desktop app) from the results.

  2. From the left panel or navigation bar in Registry Editor go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot registry key.

  3. Remove OutlookOST value

However, the exclusion of OST files is not accidental. Read more in the Microsoft Tech Community article.

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