A RHEV Storage Domain went offline after it had been extended

Issue

• Primary storage domain is offline. This occurred after attempting to add a disk to a VM. Prior to adding the disk, the storage domain had been extended.

• The extension of the storage domain appeared to be successful according to the status in the Admin Portal, however the Event Log indicated an error;

Failed to extend Storage Domain PROD_SD1

• The status of the Storage Domain in the Admin Portal is Inactive.

• With more-recent versions of VDSM, the vdsm logs on the SPM host will contain;

OSError: [Errno 19] Could not find dm device named `unknown device`

• With older versions of VDSM, the vdsm logs on the SPM host will contain;

Domain is either partially accessible or entirely inaccessible

• pvscan output will show one or more unknown device PVs;

  PV /dev/mapper/22db8d5c7b34241426c9ce900bef5335e     VG f96b201e-f9b0-4bcb-a6bf-1a5785fdfd86   lvm2 [2.00 TiB / 0    free]
  PV /dev/mapper/271b9a5d86db363b96c9ce900bef5335e     VG f96b201e-f9b0-4bcb-a6bf-1a5785fdfd86   lvm2 [2.00 TiB / 0    free]
  PV /dev/mapper/2a0406eb08bf736d76c9ce900bef5335e     VG f96b201e-f9b0-4bcb-a6bf-1a5785fdfd86   lvm2 [2.00 TiB / 1.00 GiB free]
  PV unknown device                                    VG f96b201e-f9b0-4bcb-a6bf-1a5785fdfd86   lvm2 [2.00 TiB / 2.00 TiB free]
  PV /dev/mapper/2861efb3d79bca6226c9ce900bef5335e     VG f96b201e-f9b0-4bcb-a6bf-1a5785fdfd86   lvm2 [2.00 TiB / 2.00 TiB free]