lvm snapshot module in initrd

[Jonas Bonn]

Since the LVM snapshot module is not included in the initrd/initramfs (at least for linux-686-smp), the system fails to start if there is a snapshot volume for the root volume.

The usefulness of this is that one could install an upgraded Ubuntu (e.g Dapper) on a writeable Snapshot of the original root (e.g. Breezy), and then boot into it. If something goes wrong, the original installation is untouched... if it works, you have an upgraded system at low cost since only upgraded packages have to be installed over top of what you already have installed.

[Alexandre Otto Strube (surak)]

Jonas, what happened since this post? It's been 5 months since then...

[Jonas Bonn (jonas.bonn)]

Nothing has happened, as far as I know. The snapshot module is not included by default. That said, I believe that it is possible solve this by adding the module to /etc/mkinitramsfs/modules and fixing your own initramfs.

As for the installation proposal, I still think it is a good idea (for testing or for doing safe upgrades), but LVM snapshots can be a bit fickle and I had some stability problems when I had more than one snapshot volume so I have not played with this for a while now. Perhaps unionfs is a better solution for achieving the same thing.

[Ivan Kravchenko (iv-kravchenko)]

In ubuntu karmic all works fine.
The bug seems not valid now.

[maximilian attems (maks-debian)]

Newer lvm2 hooks add the lvm snapshot module.