focal installation failed on s390x with zFCP multipath disks

[Frank Heimes]

wiping device '/dev/sda1' failed on attempt 3/4. sleeping 5s before retry
 wiping /dev/sda1 attempt 4/4
 wiping 1M on /dev/sda1 at offsets [0, -1048576]
 Failed to exclusively open path: /dev/sda1
 devname '/dev/sda1' had holders: []
 Device holders with exclusive access: []
 Device mounts: []
 Running command ['fuser', '--verbose', '--mount', '/dev/sda1'] with allowed return codes [0] (capture=True)
 fuser returned non-zero: ''
 Possible users of /dev/sda1:
 None
 finish: cmd-install/stage-partitioning/builtin/cmd-block-meta/clear-holders: FAIL: removing previous storage devices
 TIMED BLOCK_META: 11.412
 finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: curtin command block-meta
 Traceback (most recent call last):
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/commands/main.py", line 202, in main
     ret = args.func(args)
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/log.py", line 97, in wrapper
     return log_time("TIMED %s: " % msg, func, *args, **kwargs)
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/log.py", line 79, in log_time
     return func(*args, **kwargs)
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/commands/block_meta.py", line 96, in block_meta
     meta_clear(devices, state.get('report_stack_prefix', ''))
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/commands/block_meta.py", line 1821, in meta_clear
     clear_holders.clear_holders(devices)
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/block/clear_holders.py", line 628, in clear_holders
     shutdown_function(dev_info['device'])
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/block/clear_holders.py", line 301, in wipe_superblock
     _wipe_superblock(blockdev)
   File "/snap/subiquity/1735/lib/python3.6/site-packages/curtin/block/clear_holders.py", line 335, in _wipe_superblock
...

[Frank Heimes (fheimes)]

I now wiped out the multipath device / disks manually and retried, but it failed again.
This time I see _usr_sbin_fdasd.0.crash which wonders me, since there was no DASD disk active.

attached again full /var/log and /var/crash