Using the Virtual Filesystem
ownCloud offers the possibility for users to enable a virtual file system (VFS) when synchronizing data. This has the big advantage that all files and folders are visible to the Desktop App, but the files are not downloaded until the user requests to do so. Here are some of the key benefits:
Full access to files and folders without having to download them all first
Selectively sync folders and files based on user requirements
Optimize space usage on the Desktop App
The quote below gives you a brief overview of what a virtual file system is about.
A virtual file system (VFS) or virtual filesystem switch is an abstract layer on top of a more concrete file system. The purpose of a VFS is to allow client applications to access different types of concrete file systems in a uniform way. A VFS can, for example, be used to access local and network storage devices transparently without the client application noticing the difference. It can be used to bridge the differences in Windows, classic Mac OS/macOS and Unix filesystems, so that applications can access files on local file systems of those types without having to know what type of file system they are accessing.
Microsoft VFS Implementation
A sync engine is a service that syncs files, typically between a remote host and a local client. Sync engines on Windows often present those files to the user through the Windows file system and File Explorer.
- Full pinned file
The file has been hydrated explicitly by the user through File Explorer and is guaranteed to be available offline.
- Full file
The file has been hydrated implicitly and could be dehydrated by the system if space is needed.
- Placeholder file
An empty representation of the file and only available if the sync service is available.
The following image demonstrates how the full pinned, full and placeholder file states are shown in File Explorer.
Limitations and Restrictions
A virtual file system needs a root folder all synchronization items will be stored in. The following locations are not allowed as synchronization root:
The root of a disk like
A non-NTFS Filesystem
Mounted network shares
Symbolic links or junction points
Similar to OneDrive as it also uses Microsoft’s virtual file system, there are some additional restrictions which should be considered like the maximum file size, invalid file or folder names, etc. See the Restrictions and limitations in OneDrive and SharePoint for more information.
ownCloud VFS Implementation
Note that when using Windows and VFS, the Desktop app needs full control of the sync folder and its subsequent folders where the data gets stored. If this is not the case, access denied errors most likely will occur when syncing VFS data. For more details see the troubleshooting section.
New Sync with VFS enabled
To set up a new synchronization with virtual file system enabled, perform the following steps:
Add a new synchronization by clicking the + Add account button.
Enter the server address and your credentials in the following dialogs.
Select the radio button Use virtual files and set the local folder where your synchronization data will reside.
When everything is done, you should see a similar screen as below, showing that the setup completed successfully.
After the first sync, your synchronization folder will show your items with the Placeholder icon.
When opening a file, the file gets downloaded and its synchronization icon changes to Full.
Convert Full Sync to VFS
If you have full synchronization enabled, you can change to a virtual file system at any time.
Open your existing synchronization, click the … button and Enable virtual file support.
Your local files will get replaced by placeholders, thus freeing up the space previously occupied.
Convert VFS to Full Sync
You can also change the synchronization setting from virtual file system to full sync.
Open your existing synchronization, click the … button and Disable virtual file support.
A notification window will ask you to confirm before completing the conversion.
When done, your files will be fully downloaded, which you can tell by the sync icons, see the example image below. Depending on the quantity and size of the files, this may take a while.
Manage VFS from Windows Explorer
You can manage
individual files or
complete folders in the Explorer window by right-clicking on them. This opens a drop-down menu of actions that can be performed on a specific file or folder. The following example shows this on files, but it can be applied on folders too.
Create a Local Copy
To create a Full Pinned file (have a local copy of it), use the action Always keep on this device.
The state of the file will change to synchronizing.
When the local copy has been created, the state (icon) changes to Full Pinned.