Mounting Filesystem over existing directory

[Michael Conrad]

On 5/31/2012 2:04 AM, Bartos-Elekes Zsolt wrote:
> Michael Conrad wrote:
>
>> Unionfs has one problem though: the only way to get correct behavior 
>> is to merge path A and B onto mountpoint C.  (C can't be the same as 
>> A or B).
>
> Perhaps this is valid only for older versions of unionfs. I am using 
> unionfs mounted on /var that is composed of a tmpfs mounted on 
> /mnt/tmpfs, and the original /var that is on the flash (containing 
> only a few important files and directories that must be preserved 
> across reboots, like /var/lib/dpkg).
>
> $ mount | grep "unionfs"
> unionfs on /var type unionfs (rw,relatime,dirs=/mnt/tmpfs=rw:/var=rw)
>
...

On 6/1/2012 3:24 AM, Sameer Naik wrote:

> With UnionFS-2.5.11 i could merge /var/cache/etc=rw and /etc=ro at
> /etc. But evidently i have no real world testing going on here. Is
> there any specific test case i should try to confirm this?

I think I was remembering it wrong.  I think my actual problem was 
because I was trying to put the union on "/", and so the source of the 
union was *under* the mount-point.  And who knows, this might work now too.

-Mike