On Friday, 11 May 2018 19:34:42 CEST Dennis Schridde wrote:
> 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

P.S. I already found older posts [2,3] describing a similar scenario.  At the 
time a recovery was impossible for the user, but it seems that the situation 
improved somewhat since then.  However, I am still stick, with `lvconvert --
repair` asking me to repair "manually" (whatever that means), `cache_dump --
repair` not being able to operate on non-active LVs and LVM refusing to 
activate the LV as long as it has not been repaired.

[2]: https://www.redhat.com/archives/linux-lvm/2016-December/msg00013.html
[3]: https://www.redhat.com/archives/linux-lvm/2015-August/msg00008.html