Shared Folders

shared folder are the key functionality in openmediavault around which all services revolve. They will be created as subvolumes on BTRFS file systems or simple directories on all other file systems supported by openmediavault. If a shared folder is located on a BTRFS file system, then it is possible to create snapshots of it. This can be done manually or via scheduled tasks.


When a shared folder is created using the add button, the window form displays the following options:

  • Name: The logical name. This can override the path name. Typing a name here will fill the path with the same string.

  • Device: The parent filesystem associated with the shared folder.

  • Path: The relative path to the mounted device. To share the whole disk just type /.

  • Permissions: The default descriptive text will create the shared folder with root:users ownership and 775 permission mode.

Available modes

Logical name

Octal mode

Administrator: read/write, Users: no access, Others: no access


Administrator: read/write, Users: read only, Others: no access


Administrator: read/write, Users: read/write, Everyone: no access


Administrator: read/write, Users: read only, Everyone: read-only


Administrator: read/write, Users: read/write, Everyone: read-only

775 (Default)

Everyone: read/write


This is how a shared folder looks inside the config.xml database:


Some of the elements explained:

  • uuid: Internal database reference number.

  • name: logical name given to the shared folder.

  • mntentref: the associated filesystem reference. The number is in the uuid format, the fstab section in config.xml should contain a <mntent> reference with this number.

  • reldirpath: Path relative to the parent filesystem.

  • privileges: Users associated with the shared folder and their access level.

When a plugin or a service uses a shared folder it stores the uuid value only. Later on using helper scripts or internal openmediavault functions the full path can be obtained just by using the uuid. An example in shell:

$ . /usr/share/openmediavault/scripts/helper-functions && omv_get_sharedfolder_path 9535a292-11e2-4528-8ae2-e1be17cf1fde

This returns:

$ /srv/dev-disk-by-label-VOLUME1/data_general/videos

More information about helper functions.

A shared folder can be used across all over the system backend. Is available to select it in sharing services (FTP, Samba, RSync, etc.) at the same time. Plugins can use them also just by using the shared folder combo class.


  • A shared folder belongs to an internal openmediavault database filesystem entry. Is not possible to unmount the filesystem without deleting the folder configuration from the web interface.

  • If a shared folder is being used by a service (FTP, plugins, etc.) is not possible to delete it. Is necessary to disengage the shared folder from the service(s) or section(s) that is holding it before proceeding with removal. This will also prevent to unmount a device from the web interface in the filesystem section if there is still a shared folder associated with it.

  • Due to the design of the software is not possible at the moment to know what section or service is holding which shared folder.


Edit shared folder is possible, but it has some limitations. You can only change the parent device volume. Once the parent device is changed the backend will reconfigure every service that is using a shared folder and stop/start daemons accordingly.

Be aware that changing the parent device volume will not move the data from one filesystem to another.


NFS Server: Editing the parent device will not descent into /etc/fstab. Make sure you edit the share in the NFS section so the bind can be remounted.


Set the shared folder’s read and write permissions for users and groups. These settings are used by the different services (SMB, FTP and AFP). They have no effect on the permissions of the file system. It will display all the openmediavault users/groups and their corresponding permissions for the selected shared folder.

As you can see in the database example, permissions are expressed in the internal database in the same manner as permissions in Linux, simplified using the octal mode: read/write(7), read-only(5) and no access(0).

Permissions can be edited per shared folder or user.

If a permission is changed, it means a change in the shared folder database section. This database event will trigger a reconfiguration of SMB, FTP and AFP, and it will also restart all the preceding daemons. A shared folder service not using the permission information from the database entry does not get reconfigured/restarted if only a permission change occurs.

Access Control List (ACL)

Provides fine grained permission control besides the standard POSIX permissions. The usage of ACL is not recommended for the average home user. If a server is using an extensive list of users then ACL could suit better [1] [2].

The expanded ACL window displays three panels. Left one is a browser of the selected shared folder, so you can see the apply ACL to the current folder or a subdirectory and so on.

The left panel displays all current openmediavault users and system accounts and their current ACL of the selected folder. This panel actually reads ACL from the selected folder.

The bottom panel displays the standard POSIX permission of the selected folder or subfolders in a user friendly interface.

If you want just to reset linux permissions, just use the recursive checkbox and change options only in the bottom panel, and not selecting any ACL user/group in left panel.

The ACL is applied using setfacl [3] and read with getfacl [4].


  • openmediavault mounts all Linux filesystems with ACL enabled. Only native linux POSIX filesystems support ACL. The button gets disabled for HFS+, NTFS, FAT, etc.

  • ZFS provides ACL support, just need to enable the pool/dataset property.