#332 Better LVM2 support

[Redsandro]

Since I moved from hdd/MST/Partitions to a more modern ssd/GPT/LVM2 setup, it's harder to use Clonezilla.

Saving LV's, even when spanning multiple disks, seems to work fine. However;

1. Clonezilla doesn't mention the LV's when selecting something to restore. Only partitions. This is impossible to navigate without prior knowledge, and you can't select specific LV's. So you need to restore all or none.
2. When having one ext4 partition and one PV that's part of a VG on another partition, and selecting the one ext4 partition to be restored, all LV's on the VG will be restored as well (if they are not spanning multiple physical disks)
3. Restoring an LV that spans multiple physical disks is not possible. Clonezilla recommends trying cnvt-ocs-dev to convert the image(???). The image works fine as is (as illustrated below).

I'm not sure why Clonezilla won't show actual LV names from images or existing LV names to restore to when they are available, because when booting from a live USB (e.g. Linux Mint or Ubuntu) without doing anything the LV's are already detected and placed under /dev/mapper/ e.g.: /dev/mapper/vg--mint-root.

So if I want to restore a multi-device LV, I need to do this using a live Ubuntu USB rather than Clonezilla:

cat mint-vg-root.ext4-ptcl-img.gz.* | gzip -d -c | partclone.ext4 -r -o /dev/mapper/mint--vg-root

In this case the LV spans two devices. Restored correctly.

Observed using alternative testing 20190903-eoan.

[Steven Shiau]

Thanks for your feedback. Yes, so far the support is based on the partition, not LV. Will think about how to improve that iin the future.

Steven