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Direct to Cloud: "OS volume backup failed for reasons"



When attempting to back up a system protected by the Datto Direct to Cloud (DTC) Agent, you receive the error message "OS volume backup failed for reasons: volume not found, is read-only, is greater than 1TiB, is not NTFS."


  • Datto Direct to Cloud (DTC) Agent


The OS volume of the protected system:

  • Cannot be seen by the DTC agent
  • Is in read-only mode or cannot be written-to by the DTC agent
  • Is in excess of 1 TB in size
  • Is not in NTFS format


1. Ensure that the OS volume of the protected machine is capable of maintaining a stable connection to the host system.

2. Ensure that the Windows system partition and OS volume of the protected machine are not set to or entering a read-only state.

3. If the protected system's OS disk has been resized, the Direct to Cloud agent may no longer be be able to see it. Ensure that the protected system's OS volume does not exceed 1 TB in size.

4. Verify that the filesystem of the OS volume is in NTFS format. The Direct to Cloud agent cannot back up non-NTFS volumes.

5. Attempt a backup by selecting the Take backup now option from the DTC agent's tray icon.

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