CA 1 - Have more explication about ROBID.

Document ID : KB000049928
Last Modified Date : 10/07/2018
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Question:

What does the value of ROBID=254 represent?

Answer:

ROBID (Robot identifier)-

The OAM CBRUXENT exit is executed whenever a tape cartridge is inserted into the ATL. The CBRUXENT exit, which is provided by CA 1 determines the status of the tape within the TMC, then allows or disallows the entry of the tape and sets the status in the TCDB to scratch or private based on the status in the TMC. When installed, the CBRUXENT exit updates TMC fields ROBTY and ROBID to indicate the tape is in the ATL.

For basic IBM ATL processing, the OAM CBRUXEJC exit is invoked when a tape is physically ejected from the ATL. The sample CBRUXEJC exit that is provided by CA 1 clears the ROBTY and ROBID fields to indicate that the volume doesn't reside in any robot. For basic IBM ATL support, no changes to the CBRUXEJC sample exit are required.

A robotic device indicator used to distinguish between multiple robots of the same type in an installation. This field is a field that you need to assign. Typically, if an installation has three robots of the same type they are assigned the identifiers of 1,2, and 3, however the identifiers can be assigned any number up to 255.

What is happening is that CTSUXEJC is updating those fields when it detects
that an Eject failed.

         CLI   UXJNCALL,UXJEJECT       IF NOT VTS                            
         BE    NOTVTS                     THEN SKIP                          
         CLI   UXJNCALL,UXJRFAIL       FAILED TO EJECT          P5XD294      
         BE    CLROBNFO                   YES CLEAR FIELDS         P5XD294      
         CLI   UXJNCALL,UXJEXPRT       IF NOT EXPORTED VTS                   
         BNE   NOTVTS                     THEN SKIP                          
         MVI   WKATLTYP,X'81'          INDICATE VTS-IBM (VIBM)               
         MVC   WKVTXVSN,UXJSTKVS       SAVE CONTAINER VSN                    
         LA    R0,WKVTXVSN             SAVE CONTAINER VSN                    
         ST    R0,LQUERY+8                  IN PARMLIST                      
         B     MOVEDSN                                                     P5XD294      
*                                                                                P5XD294   
CLROBNFO DS    0H                                                        P5XD294      
         MVI   WKATLTYP,X'01'          IBM ROBOT                  P5XD294 ---here      
         MVI   WKATLNUM,X'FE'          EJECT FAILED              P5XD294 ---here       
         B     NOTVTS                                                       P5XD294 


When OAM attempts to eject a volume, it calls CBRUXEJC before the eject occurs. When the eject fails as in this case(because it was in use), OAM redrives the call to CBRUXEJC with the UXJRFAIL bit set. This causes our exit to update the ROBTY and ID to be updated to 01 and 254 respectively. What this means is that the volume is left in the robot without being ejected. Upon the next reject attempt(if it is not in use) the eject will complete normally.