# lvmmerge - dracut module
## Preparation
-
- ensure that the lvm thin pool is big enough
- backup any (most likely /boot and /boot/efi) device with:
```
- make a copy of the snapshot
- merge it back to the original
- rename the copy back to the name of the snapshot
-- if /restordev appears in the root, then it will restore the images *.devimage
- found in that directory. This can be used to restore /boot and /boot/efi.
- Additionally any *.mbrimage files will be restored. This can be used
- found in that directory. This can be used to restore /boot and /boot/efi
+- if /restordev appears in the root, then it will restore the images
+ found in that directory. This can be used to restore /boot and /boot/efi and the
+ MBR of the boot device
#!/bin/bash
-#
-# How to prepare:
-# - ensure that the lvm thin pool is big enough
-# - backup any (most likely /boot and /boot/efi) device with:
-# # mkdir /restoredev
-# # dev=<device>; umount $dev; dd if="$dev" of=/restoredev/$(systemd-escape -p "$dev"); mount $dev
-# - backup the MBR
-# # dev=<device>; dd if="$dev" of=/restoredev/$(systemd-escape -p "$dev") bs=446 count=1
-#
-# # ls -l /dev/disk/by-path/virtio-pci-0000\:00\:07.0
-# lrwxrwxrwx. 1 root root 9 Jul 24 04:27 /dev/disk/by-path/virtio-pci-0000:00:07.0 -> ../../vda
-# # dev=/dev/disk/by-path/virtio-pci-0000:00:07.0
-# # dd if="$dev" of=/restoredev/$(systemd-escape -p "$dev") bs=446 count=1
-# # umount /boot/efi
-# # dev=/dev/disk/by-partuuid/687177a8-86b3-4e37-a328-91d20db9563c
-# # dd if="$dev" of=/restoredev/$(systemd-escape -p "$dev")
-# # umount /boot
-# # dev=/dev/disk/by-partuuid/4fdf99e9-4f28-4207-a26f-c76546824eaf
-# # dd if="$dev" of=/restoredev/$(systemd-escape -p "$dev")
-# # ls -al /restoredev/
-# total 1253380
-# drwx------. 2 root root 250 Jul 24 04:38 .
-# dr-xr-xr-x. 18 root root 242 Jul 24 04:32 ..
-# -rw-------. 1 root root 209715200 Jul 24 04:34 dev-disk-by\x2dpartuuid-4fdf99e9\x2d4f28\x2d4207\x2da26f\x2dc76546824eaf
-# -rw-------. 1 root root 1073741824 Jul 24 04:34 dev-disk-by\x2dpartuuid-687177a8\x2d86b3\x2d4e37\x2da328\x2d91d20db9563c
-# -rw-------. 1 root root 446 Jul 24 04:38 dev-disk-by\x2dpath-virtio\x2dpci\x2d0000:00:07.0
-#
-# - make a thin snapshot
-# # lvm lvcreate -pr -s rhel/root --name reset
-#
-# - mark the snapshot with a tag
-# # lvm lvchange --addtag reset rhel/reset
-#
-# - remove /restoredev
-# # rm -fr /restoredev
-#
-# If a boot entry with rd.lvm.mergetags=<tag> is selected and there lv's with <tag>
-# dracut will
-# - make a copy of the snapshot
-# - merge it back to the original
-# - rename the copy back to the name of the snapshot
-# - if /restordev appears in the root, then it will restore the images *.devimage
-# found in that directory. This can be used to restore /boot and /boot/efi.
-# Additionally any *.mbrimage files will be restored. This can be used
-# found in that directory. This can be used to restore /boot and /boot/efi
-#
-
type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
do_merge() {