Im pretty new to unRAID and I am trying to map one of my shares to my Ubuntu VM. Currently I have edited the XML of my VM and added the following. 

<filesystem type='mount' accessmode='passthrough'>
      <source dir='/mnt/user/Ar-Cotton/Plex_Media_Library'/>
      <target dir='Plex_Media'/>
      <alias name='fs0'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x0d' function='0x0'/>
 </filesystem>

However when I restart the VM, this directory, /mnt/Plex_Media, still does not exist. How do I get my VM to recognize this path: /mnt/user/Ar-Cotton/Plex_Media_Library?

 

(Docker is not an option for me)   

You could use fstab in your Ubuntu VM and map that way.  But since I'm a linux noob there are probably better ways (like what you are trying for instance) that I don't know about.

What would I update the fstab file to say??? When I add this line to the file.

 

plex /mnt/Plex_Media      9p      trans=virtio,version=9p2000.L,rw        0 0

My VM hangs when it reboots and says An error occurred while mounting /mnt/Plex_Media 

Here is a line in fstab on my UbuntuVM that maps my download folder on another PC to a mount point in the VM image file (I.E. UbuntuVM file system):

//N54L/Download/Download+/Download /mnt/n54l/download cifs credentials=/etc/.credsagetv,rw,iocharset=utf8,file_mode=0777,dir_mode=0777,sec=ntlm 0 0

The Download folder on the unRAID server N54L is mapped to /mnt/n54l/download on my UbuntuVM using SMB.  The credentials are setup so they don't have to exist as clear text in the fstab file.

Just figured it out I had to mount my unRAID share (Ar-Cotton) with this command:

sudo mount -t nfs -o proto=tcp,port=2049 ??????_?????_??_???????:/mnt/user/Ar-Cotton /mnt/Plex_Media

Ran this command, rebooted the server, and the share appeared in an instant

Great!  Thought there would be a better way for you.