Hello!

I have an issue re-gaining access to my data.  The error messages are:
# lvchange -ay ernie/system
  Check of pool ernie/cache failed (status:1). Manual repair required!
# lvconvert --repair ernie/system
bad checksum in superblock
  Repair of cache metadata volume of cache ernie/system failed (status:1). 
Manual repair required!

How do I recover from this situation and repair the volume group?

For a full log, including the output of pvdisplay, vgdisplay and lvdisplay -a, 
please see attached log file.  If more information is necessary, please ask.

What led to this situation:
I am using one of the infamous AMD Ryzen 2400G with an AMD B350 chipset, which 
suffers from random lockups related to CPU C-states [1].  With the recent 
AGESA 1.0.0.2a firmware update and the introduction of the "Power Supply Idle 
Control = Typical Current Idle" setting, the system is stable, if it boots at 
all.  But it often takes several attempts to boot -- the failed attempts 
ending in weird firmware / EFI or CPU / idle related Linux kernel stack 
traces, which sometimes even require a hard reset, since soft-reboot (ctrl+alt
+del) sometimes has no effect, because init dies.  This was such a situation, 
where I had to reboot (ctrl+alt+del) and reset (hard) the system several 
times, at the end of which everything seemed fine, except that dracut was 
timing out when activating the disks.  Debugging the situation using a Fedora 
28 live system resulted in the attached log file.

--Dennis

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=196683