On 05/31/2011 07:54 AM, Thomas Bächler wrote:
Am 31.05.2011 03:21, schrieb Gerardo Exequiel Pozzi:
Hi
* With 2.6.39 there is no aufs2 support, at least for a long time[#1]. * I think that back in time with unionfs is not desirable, needs a complete kernel patch. * union-fs-fuse does not work good.
What about using the method like in Fedora? (basically a device-mapper with a snapshot in tmpfs).
This change from file-to-file level to block-to-block logic. This actually sounds pretty cool. However, I don't understand how it works: The squashfs file system is a read-only one, how can we put that into a block-level snapshot?
Yes, but there are at least one downside: since is not an union-fs, there is no concept of layers. We are currently using "overlay" thats overlap some files on the layer "root-image". With the others layers like "core-pkgs" and "lib-modules", there are no overlap and can be replaced by a simple mount point. Of course this "overlay" can be merged at build time on "root-image". About your question: The squasfs image contains only one file... an image of and 4 GiB ext4. There is another small squasfs image with another one file inside that is a "lvm snapshot". So dm device is made via these images loopback mounted... The code is here http://git.kernel.org/?p=boot/dracut/dracut.git;a=tree;f=modules.d/90dmsquas... -- Gerardo Exequiel Pozzi \cos^2\alpha + \sin^2\alpha = 1