[Unionfs] Kernelpanic after trying to mount a union (2.6.16-ck1, unionfs-20060321-0427)

[Josef Sipek]

On Sun, Mar 26, 2006 at 12:48:46PM +0200, Ferdinand Hübner wrote:
> Josef Sipek wrote:
> 
> > You want both directories to be read-only? You should have at least the
> > highest priority branch rw. If you want the whole union to be ro, make
> > the highest priority branch rw, but make the mount ro. Eg.
> 
> Thanks, it does work when I mount the leftmost branch rw. The reason I
> did mount both directories ro was, that directories on the ro branch got
> copied into the rw branch (I didn't do that...). So I had these
> directories on both filesystems. I don't know if this is an expected
> behaviour... I want to avoid having duplicate directories (and the files
> in them) in the branches! Is there any option I can pass to unionfs, so
> that it doesn't do that? The ro-branch is ~120G with < 100MB free space,
> the rw-branch ~250G with 100G+ free.

The only way to disable copyup is to make all the branches rw. This will
make any changes to files go to whatever branch the files are on. So, if
anything you might want to move some of the files from the 120GB disk to
the 250GB disk and then union them.

I must say one thing...unionfs isn't really made to "expand" storage
like you want to. Once you fill up one disk any write that tries to take
more storage on that disk will fail with "No space left of device."

Jeff.