Description of problem:
Installation tested on a POWER9 LPAR.

Custom partitioning with / using RAID1.
Failure occurs after beginning of installation, when partitions are created.

Note the same test with / using RAID0 succeed.

Version-Release number of selected component:
anaconda-31.22.2

The following was filed automatically by anaconda:
anaconda 31.22.2 exception report
Traceback (most recent call first):
  File "/usr/lib/python3.7/site-packages/blivet/formats/fs.py", line 410, in _create
    raise FormatCreateError(e, self.device)
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/formats/__init__.py", line 513, in create
    self._create(**kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/deviceaction.py", line 634, in execute
    options=self.device.format_args)
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/actionlist.py", line 327, in process
    action.execute(callbacks)
  File "/usr/lib/python3.7/site-packages/blivet/actionlist.py", line 48, in wrapped_func
    return func(obj, *args, **kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/blivet.py", line 106, in do_it
    self.devicetree.actions.process(callbacks=callbacks, devices=self.devices)
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/storage/installation.py", line 50, in turn_on_filesystems
    storage.do_it(callbacks)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation_tasks.py", line 450, in run_task
    self._task(*self._task_args, **self._task_kwargs)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation_tasks.py", line 484, in start
    self.run_task()
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation_tasks.py", line 305, in start
    item.start()
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation_tasks.py", line 305, in start
    item.start()
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation_tasks.py", line 305, in start
    item.start()
  File "/usr/lib64/python3.7/site-packages/pyanaconda/installation.py", line 397, in run_installation
    queue.start()
  File "/usr/lib64/python3.7/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/threading.py", line 280, in run
    threading.Thread.run(self)
blivet.errors.FormatCreateError: (FSError('format failed: 1'), '/dev/mapper/fedora_zz14--lp5-00')

Additional info:
addons:         com_redhat_kdump
blivet-gui-utils.log: 
cmdline:        /usr/bin/python3  /sbin/anaconda
cmdline_file:   BOOT_IMAGE=/ppc/ppc64/vmlinuz inst.stage2=hd:LABEL=Fedora-S-dvd-ppc64le-31 ro ip=9.40.195.32::9.40.195.1:255.255.255.0:zz14-lp5:env2:none nameserver=9.101.4.100
dnf.librepo.log: 
executable:     /sbin/anaconda
hashmarkername: anaconda
hawkey.log:     INFO Aug-29 12:50:42 === Started libdnf-0.35.3 ===
kernel:         5.3.0-0.rc5.git0.1.fc31.ppc64le
product:        Fedora
release:        Fedora release 31 (Thirty One)
release_type:   pre-release
type:           anaconda
version:        31

Potential duplicate: bug 1745940