Created attachment 1507698 [details]
Exception report

Description of problem:
I used mdadm to create a raid1 with two disks and partion it,then i removed one disk from the raid.After this, i try to install system but it will report exception.It is interesting that if i remove another one disk and remain the oringinal one,then system installation will success.
Information detail:
anaconda 21.48.22.134-1 exception report
Traceback (most recent call first):
  File "/usr/lib/python2.7/site-packages/blivet/devicelibs/mdraid.py", line 378, in name_from_md_node
    raise MDRaidError("name_from_md_node(%s) failed" % node)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 926, in addUdevPartitionDevice
    name = mdraid.name_from_md_node(name)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 1240, in addUdevDevice
    device = self.addUdevPartitionDevice(info)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 2306, in _populate
    self.addUdevDevice(dev)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 2239, in populate
    self._populate()
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 495, in reset
    self.devicetree.populate(cleanupOnly=cleanupOnly)
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 190, in storageInitialize
    storage.reset()
  File "/usr/lib64/python2.7/threading.py", line 765, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/threads.py", line 227, in run
    threading.Thread.run(self, *args, **kwargs)
MDRaidError: name_from_md_node(md127p1) failed

Local variables in innermost frame:
node: md127p1
name: None
md_dir: /dev/md


Version-Release number of selected component (if applicable):
python-blivet-0.61.15.69-1.el7.noarch.rpm

How reproducible:


Steps to Reproduce:
1.A normal system with two vacant disks like sdb,sdc. 
2.mdadm -C /dev/md0 -l 1 -n 2 /dev/sdb /dev/sdc
3.Excute "fdisk /dev/md0" to create a partion on /dev/md0.
4.mdadm -f /dev/md0 /dev/sdc;mdadm -r /dev/md0 /dev/sdc
5.Shutdown and install system.
Actual results:
It will report exception.

Expected results:
Installation success.

Additional info:
If remove sdc won't reproduce the problem,then try to redo the"Steps to Reproduce" but remove sdb instead of sdc.
I also tried to install Fedora28 aside from rehat7.5.There was no problem with Fedora28.
During the installation of Fedora28 I switched to commanline and found a mdadm configure file--mdadm.conf under directory /etc/,but I didn't find it in redhat7.5.
So I added the the same mdadm.conf to squashfs.img of redhat7.5 and recreate iso.The was not exception report any more when I installed system with new iso.