Aufs: save to entire partition

There is, or rather was, a serious limitation with Aufs if we choose to save a session to the entire partition rather than a file.

Booting off Flash drive or frugal hard-drive installation, at first shutdown we have the option of saving to the entire partition if it is a Linux filesystem. However, with Aufs that meant we could no longer mount SFS files, as Aufs saw a conflict if the the SFS files are in the partition (and thus present on one layer of the layered filesystem.

Unionfs is able to handle this, and after discussion with J. R. Okajima he provided a patch for Aufs to permit an SFS to be present on one layer and mounted via loop device as another layer. Reported on my blog:

I have just tested this. I installed Wary 020 onto a Flash drive which has a ext3 filesystem. I also placed an OpenOffice SFS file on the Flash drive. At first shutdown I chose to save to the entire partition. Booting again, Wary was able to mount the main Puppy f.s. wary-020.sfs without having to copy it to RAM first, and was able to mount the OpenOffice SFS file. This is great, another bug bites the dust!

Note, the patched Aufs is in my kernel PET.

Posted on 26 Apr 2010, 12:08


Posted on 26 Apr 2010, 21:38 by Raymundo Dionicio
An Old One :)
This is an Important One (bug).

Okajima is a gentleman.