Issue is already reported to upstream
Patch for PPC64LE already exists in upstream. See
This bug is valid only for s390x. The rest architectures are ok.
This is the same bug as for RHEL-6.8:
So... Small change:
x86_64, ppc64, ppc64le - OK
s390x, aarch64 - FAIL - don't create ISO file
# rear -v mkbackup
Relax-and-Recover 1.17.2 / Git
Using log file: /var/log/rear/rear-ibm-z10-73.log
Creating disk layout
Creating root filesystem layout
Copying files and directories
Copying binaries and libraries
Copying kernel modules
# echo $?