When you encounter the error message Error: Got error 28 from storage engine
usually it means that there is no more free disk space on the server where MySQL is located. QueueMetrics creates temporary tables when it runs, but without free disk space, it cannot work.
You need to:
- clean up the disk;
- make a database dump;
- do a repair of all tables on the database see: Repair MySQL;
- restart your Uniloader/Qloader.
It is possible - though unlikely - that some tables will not be recoverable. In this case you need to go back to a previous back-up.