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Virtual Files

Christian Kamm edited this page Jul 17, 2019 · 1 revision

Virtual files / Files-on-demand

Traditionally the ownCloud Desktop Client downloads the contents of all files to the local computer. Enabling virtual files (vfs) mode changes that and allows file contents to be downloaded on demand instead.

When the mode is enabled files on the local disk may be "virtual" files (also known as "placeholder" files). They represent files on the server that have not been downloaded yet. Their content will be downloaded on demand, for example when a user opens the file.

The file context menu can be used to free up space by deleting the local copy of file contents.

Benefits and Drawbacks


  • Reduces amount of disk space needed.
  • Reduces amount of network data used.
  • Reduces setup time, as much less data needs to be transfered initially.
  • Reduces synchronization time as remote changes to files that aren't available locally just change metadata.


  • Need to wait for download to finish when opening a virtual file.
  • Downloading may be impossible if there is no internet connection or a server outage.

Platform differences

The best support for virtual files is currently available when running an up to date Windows 10. There, the ownCloud Desktop Client can make the virtual files look just like regular files, distinguished by a cloud icon. See for details.

On MacOS and Linux virtual files currently appear as tiny files with a ".owncloud" extension.

Enabling and disabling

Virtual files mode can be enabled and disabled for each sync folder in an account. Both the folder and account wizard have new options for enabling it during folder creation. It can also be enabled and disabled on existing folders by opening the folder's "..." menu and clicking "Enable virtual file support (experimental)..." or "Disable virtual file support...".

Note that selective folder sync is not compatible with this mode: Folders which were previously marked as excluded will be marked as online-only and will become visible on the local filesystem. Existing selective sync settings will be deleted.


To make sure that file contents are available and are kept up to date:

  • Open the local sync folder in the file explorer.
  • Select files and folders.
  • Open the context menu and select "ownCloud -> Make always available locally".

When new files are added to a folder on the server that was marked as "always available locally" the new file will be downloaded and also be marked as such. Otherwise new files on the server will start out as a virtual file locally.

To free up local disk space by deleting the local copy of file contents:

  • Open the local sync folder in the file explorer.
  • Select files and folders.
  • Open the context menu and select "ownCloud -> Free up local space".
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