hello, i maintain an unofficial btrfs initcpio hook in AUR: http://aur.archlinux.org/packages.php?ID=33376 the hook provides rollback support among other (future) features. hook is also required for anyone using a multi-device btrfs setup. i would like to start/be included in discussion involving btrfs integration into AIF, and other aspects of Arch. i think it would be nice for users to be able to have the option to use the new filesystem by default-ish, and have the tools needed to work with it. specifically, it would be really neat to have "rollback" support in a "rolling" distro. people would likely be more willing to ride the edge of the testing repo if they knew they could simply reboot and all could be well again when things did break. right now, the rollback feature provided by the hook is volatile, but this is only an implementation detail. what i mean by this is once you rollback, you CANNOT promote the "rollback" subvolume to be the new "active" (default) subvolume; you must fix the default subvolume manually and reboot again. anything you do in rollback mode will be lost on the next rollback. this is something i intend to change, but i need some input from other developers. what i propose is to do away with installing the system onto the default subvolume (like a typical installation); system will be installed to it's own subvolume (/root/__active). something like this: . ├── home │ ├── __active │ ├── __rollback │ ├── snap_11-11-1111_11-11-11 │ └── snap_22-22-2222_22-22-22 └── root ├── __active ├── __rollback ├── snap_11-11-1111_11-11-11 └── snap_22-22-2222_22-22-22 this is the "subroot" structure; underneath your / [root]. "." is the original default subvolume. /root/__active is your "primary" (default) system. /root/ __rollback is a volatile copy of a /root/snap_XX (you boot into this [__rollback] when you "rollback"). since snap_XX gets copied to __rollback... if you decide you want to ditch your changes to __active (since it's messed up anyways), you just replace __active with __rollback (delete/rename), reboot, and voilà! your system's __active subvolume works again, and none of your snapshots got messed with. same logic for /home/__active and /home/__rollback (and snap_XX) except you wouldn't have to reboot... maybe we can create login manager ([xkg]dm) hooks to remount your home folder with a "rollback" on the next logout or something? who knows. we could take a snapshot after install (on the very first boot), called "__original" or something, then users would always have a copy of their system immediately after installation; they could revert/use/delete that if they wanted to at any time. however, this setup would require mounting the default subvolume somewhere else in order to gain access to the "subroot" structure, but it would guarantee that you could not destroy your system no matter what you did to your / [root]. any ideas on this? my attempts to generate interest in the forums are falling on deaf ears so i thought i'd try my luck here. thanks, C Anthony
