Public bug reported: I am working on a project which allows the installation of multiple Linux live ISO images on a single USB flashdrive.
http://sourceforge.net/projects/multibootusb/ We would like to make use of the Ubuntu live ISO feature wherein persistent changes to the live ISO filesystem may be saved on the same USB flashdrive, and restored across reboots. >From inspection of the casper source code, it appears that persistent data may >be stored in two different filesystem images; one for system data, and the other for user data. Since our project expects that several bootable distributions will coexist on the same flashdrive, it would clearly be a bad thing if changes to one operating system affected the others, and thus persistent system data ought NOT to be shared between them. However, it would be quite inconvenient for users if files that they had saved while running one distribution were not available from another, and therefore persistent user data SHOULD be shared between the installed distributions. Unfortunately, it appears that it is not currently possible to accomplish this outcome, because the names of the persistent filesystem images are not configurable; they must be "casper-rw" for the system data, and "home-rw" for the user data. The only thing that may be configured is the directory within which these two filesystem images reside. Thus either both filesystems, or neither, may be shared between different distributions. It is not possible to have one shared and the other unshared. The attached patch removes this limitation, by making the full pathnames of the two persistent filesystem images independently configurable. It does this by introducing two new initrd boot options: "persistent-root=" and "persistent-home=". These were chosen in conformance with the existing boot option "persistent-path=", whose function remains unchanged if neither of the new options is used (except that it is no longer necessary to also specify the flag option "persistent" when it is present). It is intended that the new options will specify the full pathnames of the persistent filesystem images (or possibly only one of them), relative to the root directory of some attached device, as does the "persistent-path=" option. If they are not used, the code functions exactly as it did before, ensuring full backward compatibility with other interacting software. There is some amount of overlap with the code for "snapshots", which I did not entirely understand, but I took care that its function would be completely unaffected. I would point out that the current code contains this comment: # FIXME: add a custom mounts configurable system I believe that this is exactly what I have just done. ******* I am aware that a new version of Ubuntu will be released soon, according to the standard schedule. Because this patch is extremely small and self-contained, yet provides a significant improvement in functionality, as described above, I would ask that it be considered for the upcoming release. I should say that my description of multiple (Ubuntu-based) distributions coexisting on the same flashdrive, and sharing the same set of persistent user data, is not hypothetical. It is already working perfectly in our development version. We cannot yet enable (unshared) persistent system data, for reasons already discussed, but this will also be functional as soon as this patch is accepted into released ISO images. Thanks for your consideration. -- Ian Bruce ** Affects: casper (Ubuntu) Importance: Undecided Status: New ** Patch added: "this patch provides the requested new functionality" https://bugs.launchpad.net/bugs/1159464/+attachment/3594167/+files/casper_1.330.diff -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1159464 Title: make persistent storage pathnames fully configurable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1159464/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
