+++ This bug was initially created as a clone of Bug #1916851 +++ OSP 13 to OSP 16.1 upgrade process recommends the usage of ReaR to backup undercloud and control plane. The backup image for the undercloud was generated as instructed but during recovery the filesystems couldn't be mounted.
On the documentation for osp13 [1] on step "3.1. Install the Required Packages" we need to add step 2, something like 2.- Delete schedule rear cron task [root@controller-x ~]# rm -f /etc/cron.d/rear The rear package schedules a backup everyday at 1.30, this tasks needs to be deleted to avoid future issues [1] .- https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/undercloud_and_control_plane_back_up_and_restore/install-and-configure-rear-osp-ctlplane-br
Updated doc: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/undercloud_and_control_plane_back_up_and_restore/install-and-configure-rear-osp-ctlplane-br#install-the-required-packages-osp-ctlplane-br