Errors accessing virtual cloud storage files

Notes about virtual cloud storage

OneDrive, Google Drive and similar cloud storage apps can keep files "on demand": the file shows on the local disk, but its content stays in the cloud until something opens it. Magnus Box can't reliably read these files, even though the user can see and open them. Backing them up is only possible if a local copy of the files is available to the backup app. Keeping local copies uses local disk space and can cause a lot of downloading.

Jump to an error:

• "Media is write protected" backing up OneDrive with VSS
• "Access to the cloud file is denied" backing up OneDrive
• "G:\ not found" backing up Google Drive (File Stream) items

OneDrive

To save disk space, OneDrive (and some other cloud storage providers) keeps some files only "virtually" on the local disk, and downloads them from the cloud when they're opened. This is OneDrive's Files On-Demand feature.

Error "Media is write protected" backing up OneDrive with VSS

When you turn on Take filesystem snapshot for a Protected Item, Magnus Box takes a VSS snapshot of the disk. The snapshot is read-only.

When the Protected Item includes the OneDrive folder, OneDrive can't download on-demand files into the read-only snapshot. That causes the "Media is write protected" error.

In this situation, the OneDrive data is not being protected by Magnus Box and can't be restored.

To work around it, create two Protected Items:

• one with Take filesystem snapshot turned on, which excludes the OneDrive folder; and
• a second with Take filesystem snapshot turned off, which includes only the OneDrive folder.

If OneDrive has to download a lot of data from the cloud, backing up the OneDrive folder can cause a lot of downloading.

Error "Access to the cloud file is denied" backing up OneDrive

This error means the file isn't stored on the local PC, and OneDrive's filesystem driver refused to download it on demand for Magnus Box to read.

To fix it, make the files available locally:

• For specific folders: in File Explorer, right-click the folder inside OneDrive and choose Always keep on this device.
• For everything: turn off Files On-Demand in the OneDrive settings. Right-click the OneDrive icon in the system tray, open Settings and find the Files On-Demand option. The exact menu names depend on the OneDrive version.

Either way, the files then take up local disk space, which may not be acceptable on some devices.

Google Drive

Error "G:\ not found" backing up Google Drive (File Stream) items

Google Drive for desktop (previously called Google Drive File Stream) creates a virtual drive, for example G:\, that streams data from the Google account on demand, using only a small local cache.

The virtual drive exists only in the logged-in user's session.

Magnus Box runs all backups (both manual and scheduled) as a service user account. Each login session has its own set of drive letters, so the service session doesn't see that G:\ exists.

The drive is still visible in the backup app's file picker, because the picker runs as the logged-in user for performance reasons.

Ways around it:

• In Google Drive for desktop, switch My Drive from streaming to mirroring files. Mirrored files are stored in a normal local folder, which you can back up like any other folder. This uses local disk space for the whole drive.
• Use a third-party tool that may be able to mount Google Drive for all users, for example rclone mount. Test it with a scheduled backup before relying on it. The data is downloaded from Google during every backup, which can cause a lot of inbound traffic.