This bug was initially created as a copy of Bug #1747468

I am copying this bug because: it applies to RHEL7 as well



Description of problem:

The code in PR https://github.com/rear/rear/pull/1806 (BZ #1450667) added support for restoring Thin volumes into ReaR 2.4.
Unfortunately it appears it doesn't work as planned.

1. When restoring the exact same system (which already had the VG containing the thin volumes configured at the time of the restore), the code used to delete the Thin pool after using vgcfgrestore is failing due to line 111 not returning an error, making line 112 return an error now

usr/share/rear/layout/prepare/GNU/Linux/110_include_lvm_code.sh:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
105     lvm lvs --noheadings -o lv_name,vg_name,lv_layout | while read lv vg layout ; do
106         # Consider LVs for our VG only
107         [ \$vg == "$vg" ] || continue
108         # Consider Thin Pools only
109         [[ ,\$layout, == *,thin,* ]] && [[ ,\$layout, == *,pool,* ]] || continue
110         # Remove twice, the first time it fails because of thin volumes in the pool
111         lvm lvremove -q -f -y \$vg/\$lv || true    <-- HERE
112         lvm lvremove -q -f -y \$vg/\$lv
113     done
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

At the time PR1806 it was not the case, so there must have been some changed in LVM ...

2. When restoring a new system with same disk capacity (hence with clean new disk, this can be emulated by using "pvremove --force --force /dev/sdaX"), "vgcfgrestore" run but then "lvm lvremove" (line 111) fails with an unrecoverable error

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
+++ lvm lvremove -q -f -y rhel/pool00
  Thin pool rhel-pool00-tpool (253:2) transaction_id is 10, while expected 6.
  Failed to update pool rhel/pool00.
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------


Version-Release number of selected component (if applicable):

rear-2.4 including Upstream ReaR


How reproducible:

Always


Steps to Reproduce:
1. Install a system with LVM Thin Provisioning and multiple volumes, keep the swap as a standard LVM volume

  /: thin
  /var: thin
  /home: thin
  /tmp: thin
  swap: linear

2. Create a rescue ISO
3. Recover the system

Actual results:

See above


Expected results:


Additional info:

It looks like to me "vgcfgrestore" cannot be used at all as soon as there is a Thin volume.
I'm pretty sure it was working at the time PR1806 was submitted (June 2018), I need to test this again.

For the demo, I've added a linear swap device because additionally, in scenario 2 ("When restoring a new system"), the swap volume gets restored by vgcfgrestore but doesn't get activated, causing an error when formatting the swap (/dev/vg/swap is not present ...), this is yet an additional issue...