1.208: How do I read a 5Gbyte tape on a 2Gbyte drive?

To read a 5Gbyte tape on a 2Gbyte drive, the
tape needs to have been created with a density setting of 20.

The following is from IBM's electronic ASKSUPPORT repository:
  
   R: The 7208 011 5 GB tape drive has various density settings which are
      as follows:
  
     +-------+--------------------------+
     | DENSIT| DESCRIPTION              |
     | SETTIN|                          |
     +-------+--------------------------+
     | 140   | Writes in 5.0GB mode and |
     |       | will enable data com-    |
     |       | pression; also, to do    |
     |       | compression you must use |
     |       | "DATA COMPRESSION = yes" |
     +-------+--------------------------+
     | 21    | Writes in 5.0GB mode and |
     |       | will NOT do data com-    |
     |       | pression                 |
     +-------+--------------------------+
     | 20    | Writes in 2.3GB mode and |
     |       | will NOT do data com-    |
     |       | pression                 |
     +-------+--------------------------+
     | 00    | Factory power-on default |
     |       | for 5.0GB data com-      |
     |       | pression mode            |
     +-------+--------------------------+
  
     The density setting of the 7208 011 must be 20 for it to make a tape
     that is readable by the 7208 001.