On Tue, Nov 25, 2014 at 8:22 PM, Duncan <1i5t5.dun...@cox.net> wrote: > From my perspective, however, btrfs is simply incompatible with lvm > snapshots, because the basic assumptions are incompatible. Btrfs assumes > UUIDs will be exactly what they say on the label, /unique/, while lvm's > snapshot feature directly breaks that uniqueness by copying the (former) > UUID, thus making the former UUID no longer unique and thus no longer > truly UUID.
The seed device has a mechanism to change volume UUID without rewriting a bunch of stuff in the original, the gotcha is that it requires adding a device. man fsfreeze says "fsfreeze is unncessary for device-mapper devices. The device-mapper (and LVM) automatically freezes filesystem on the device when a snapshot creation is requested." So if it's possible to communicate snapshotting/freezing to the fs at snapshot time, then maybe btrfs could 'btrfstune -S 1' the volume in the snapshot. That way that snapshot actually contains a btrfs seed device, which is read only. At least the snapshot copy isn't going to get obliterated in an accident; even though most people would probably want the origin LV to be protected while considering the snapshot disposable. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
