Issue

• lvm commands do not show my physical volume, volume group, or logical volume anymore.
• When running pvscan "unknown device" is seen for a device that is being used as a physical volume in a running configuration.

  PV unknown device   VG VolGroup13      lvm2 [656.00 GB / 6.00 GB free]

• lvm commands are reporting "volume group does not exist" even though it should exist.
• After multipath config changes, OS cannot see the lvm volumes anymore.
• Data was written to the first megabyte or head of all physical volume disks
• LVM metadata appears to have been lost from one of the disks of a 2 disk LVM.
• After unpresenting storage devices from the system, certain volume groups are throwing "Couldn't find device" errors and will not activate:

 Couldn't find device with uuid paH2Cp-w92t-lIz2-WznV-ihDJ-dg8M-oFUpMa.
    There are 1 physical volumes missing.
  PV             VG     Fmt  Attr PSize  PFree
  /dev/sda2      rootvg lvm2 a-    9.69G    0 
  /dev/sdb1      appsvg lvm2 a-   79.97G    0 
  /dev/sdd1      rootvg lvm2 a-    4.97G 1.97G
  unknown device appsvg lvm2 a-   79.97G    0 

• Removed redundant multipath device, now the system is not showing any LVs.