Now that overlayfs went into the 3.18 kernel I've had a look if this could be used in our installation environment. = what we need = We have to combine several ro (squashfs) filesystems into the root fs. And the final fs should be writable. Also, it should be possible to easily add and remove fs images. = what we currently do = A script integrates new filesystem images by adding symlinks as needed. = what overlayfs (currently) can do = First, here's how to use it: mount -t overlay overlay -olowerdir=/foo,upperdir=/bar,workdir=/xxx /mnt where /xxx must be on the same fs as /bar but not below /bar. (That's why upperdir must be a writable fs atm, btw.) You can combine exactly *two* filesystems the 'upper' one must be writable. (Doc says you can use two ro filesystems but that is not true atm and there's a note in the sources that they might fix this.) There's no way to combine more than two filesystems except by step-by-step doing overlay mounts. This seems not much of a problem at first but in practice is quite annoying as there are conditions to fulfill; namely you have to have a 'work' directory in the upper fs that must be a separate subtree from the '/' dir in the upper fs. So you would have to make every squashfs writable first by overlaying it with a tmpfs. And then add it to the existing stack. We combine 8 images atm in Factory, so that would be about 16 overlay mounts. Plus you cannot easily unmount parts of this beast as any process rw-opening a file and holding it open (say, even some log or tmp) will block the umount. Plus anything you logged into log files will be lost when you unmount the upper level. This construction seems to be too impractical to me. = conclusion = Not yet. Steffen -- To unsubscribe, e-mail: yast-devel+unsubscribe@opensuse.org To contact the owner, e-mail: yast-devel+owner@opensuse.org