Mikolos,
thanks for joining the party.
Am 03.03.15 um 16:14 schrieb Miklos Szeredi:
Atom2,
The use case behind that is to be able to backup only files from the
upperdir for several systems sharing a common lowerdir filesystem. I have
used that (scripted approach via rsync) now for quiet some time and a few
kernels back and it seemed to have worked very well.
Why don't you just back up the upper directory itself instead of
messing around with device numbers?
I am not aware of any such option, but if you could explain that a
little bit more in detail, I am happy to explore other options.
Just for everybody to be on the same page: In my use case the r/o
lowerdir's root directory is also the root of my file system (which is
shared across many systems) from which (all) the systems boot. Using an
initramfs during the boot process, the upperdir file system (which is
different per system) is then r/w overlay-mounted over the common r/o
lowerdir's root directory in order to catch any r/w access to the file
system.
So in essence and according to my understanding there's no direct access
to (only) the r/w upperdir (or only the lowerdir) from within any of the
running systems other than using the device field to see where a file
system entry actually exists - at least that's my current understanding.
But again, I am happy to learn ...
Regards Atom2
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