Re: understanding mount_union

[Eric Haszlakiewicz <erh%nimenees.com@localhost>]

On May 14, 2014 5:26:36 AM EDT, Patrick Welche <prlw1%cam.ac.uk@localhost> 
wrote:
>On Tue, May 13, 2014 at 11:28:11PM -0400, Eric Haszlakiewicz wrote:
>
>Thanks to hints from Malcolm Herbert, it seems that rather than
>  <above>:/var/upper on /var/lower type union (local)
>I need: mount_union -b /var/lower /var/upper
>  <below>:/var/lower on /var/upper type union
...
>I can't say that I understand why the two cases are different.
>"However, uniondir remains the mount point." in the -b option
>explanation seems rather important.
>

Good to hear you got it working the way you wanted.

With and without -b do essentially the same thing, just changing where the 
results are visible.

With -b:
  Combine the set of files in /var/upper with those in /var/lower, with 
/var/upper overriding the lower layer,
    and make that visible at /var/upper

Without -b:
  Combine the set of files in /var/upper with those in /var/lower, with 
/var/upper overriding the lower layer,
    and make that visible at /var/lower

Eric