Exporting a RHEV VM failed with "Volume already exists"

Issue

• VM Export did not complete.

• The two smaller disks of the VM had finished exporting, the large disk reached it's full size and then the export failed.

• The vdsm logs contained;

VolumeAlreadyExists: Volume already exists: ('3fa0f4a8-72aa-4fd6-93e2-175c16e0ae7c',)

• The engine log contained;

2015-02-22 12:20:34,107 ERROR [org.ovirt.engine.core.bll.SPMAsyncTask] (DefaultQuartzScheduler_Worker-79) [5e415a4a] BaseAsyncTask::LogEndTaskFailure: Task 88a790c5-6303-46d5-8279-06514222ed35 (Parent Command ExportVm, Parameters Type org.ovirt.engine.core.common.asynctasks.AsyncTaskParameters) ended with failure:
-- Result: cleanSuccess
-- Message: VDSGenericException: VDSErrorException: Failed in vdscommand to HSMGetAllTasksStatusesVDS, error = Volume already exists,
-- Exception: VDSGenericException: VDSErrorException: Failed in vdscommand to HSMGetAllTasksStatusesVDS, error = Volume already exists