[Errno 13] Permission Denied during ShadowSnap backup job

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1. Scope

This article describes the causes and possible solutions for an [Errno 13] Permission Denied error during a ShadowSnap backup job.

2. Cause

Possible causes for this problem:

  • Database locks that occurred with earlier versions of ShadowProtect and ShadowSnap causing files to become inaccessible.
  • Domain permissions may be preventing access to shares hosted by the Datto that the ShadowSnap agent uses to transfer backup information.
  • Datto device is joined to the domain and the domain is not configured properly.
  • For encrypted agents, if the Datto is unable to properly clean up iSCSI targets it is hosting to capture transferred backup information due to an unexpected interruption, subsequent backups may fail with this error message.

3. Solution

3.1 Initial Troubleshooting

If you have not done so already, follow the preliminary steps in the Start Here article.

  1. Check if the Datto device is joined to the domain. If it is, remove the device from the domain.
  2. Enable Share Compatibility from the Configure Agent Settings → Advanced → Share Compatibility Mode page of the device GUI.
  3. Force a differential merge from the Configure Agent Settings → Advanced → Force Differential Merge page of the device GUI.
  4. If the issue persists, attempt a ShadowProtect backup to a NAS share on the Datto appliance. Observe whether or not the backup fails in the same state. If it does, investigate the configuration of your domain permissions, which may be preventing access to shares hosted by the Datto appliance.

3.2 Clear iSCSI Targets

1. Open diskpart via the Windows command line, and run the command command automount scrubThis will prune any of the iSCSI targets that are currently stuck on the host machine.

2. After running the scrub, confirm that the target has been removed by opening the Windows iSCSI Initiator, and looking for any connected devices. If other encrypted agents are backing up to the same device, you may see other devices reporting as inactive. The naming convention of the targets will allow you to distinguish which targets are created for which agents. iSCSI connections to the Datto appliance contain the name of the Datto device, the agent IP/hostname, and randomly-generated characters for each volume needed.

iscsiInitiator.JPG
Figure 4: iSCSI Initiator

3. After clearing any hung iSCSI connections, attempt another backup.


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