Sun StorageTek 9840 Tape Drive
 
Sun StorageTek T10000 Tape Drive
 
Sun StorageTek 9940 Tape Drive
 

PLA-Support>Sun Systems>TAPE>Tape Hardware>SN-TP: STK T-Series Drive
 

In this Document

Goal

Solution

Applies to:

Goal

 Identify and define a tape drive positioning error.

Solution

When the host job wants to position the tape to a certain block, it will issue a Locate or Space command.  A locate command is followed by a blockid that job wants the tape drive to position to.  A Space command can come in the form of either a Space block or Space file command. The command is just Space and the arguments given to the command determine if it is a Space Block or Space File. The argument also determines if the drive is to Space forward or backward.

After a Locate or Space command completes, it is common for the job to verify that it is in the correct place on tape.  It may issue a Read Blockid command to the drive where the drive returns the current blockid which is then matched up by the job to verify correct positioning.   Some applications write the blockid in a header that is in the first few bytes written to every block. This is another method that the job can use to verify correct positioning.

If any of these verification methods fail then it is called a positioning error.

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