Using STOP,IMMED to shutdown XCOM

Products

• XCOM Data Transport
• XCOM Data Transport - z/OS

Issue/Introduction

What happens when a STOP,IMMED is issued to shutdown XCOM?

Environment

XCOM Data Transport for z/OS

Resolution

With STOP,IMMED, all shutdown processing (closing the history and RRDS files, etc) is DONE except the following:

• Transfers are just stopped - not suspended. No cleanup is done. To the partner it just looks like the other server went down. The partner will handle the transfer in the same way it would if the z/OS server went down. 
• When it comes back up, processing will restart for type=schedule transfers (given that retries are configured).
• Partial datasets being written on MVS will not have an EOF on them, but the restart will attempt to reposition into the file with a POINT macro (which does not require the EOF). If it cannot, it will restart from the beginning. 
• TYPE=EXECUTE transfers will have to be cleaned up manually. 
• XCOM does not wait on the PSO subtask - XCOM just takes it down.

Additional Information

NOTE: See the STOP section on doc. page  Using the MODIFY Commands i.e. 
IMMED
Stops XCOM Data Transport immediately and unconditionally, even when transfers are in progress. Normal cleanup of transfer requests does not occur. Unpredictable results and abends can occur.

An example of these symptoms being reported is below:
System automation commands are

Shutnorm:
  CMD=(PASS1,,'MVS F XCOM,STOP')       
  CMD=(PASS2,,'MVS F XCOM,STOP,IMMED') 

XCOM stopped responding after the PASS2 command in System Automation and started generating SYMPTOM DUMP which filled up the JES Spool. 

SYSLOG:
*****
2024144 07:05:12.31 AWRK19RA 00000290  F XCOM,STOP   
S0155742 00000090  XCOMM0013I STOP                                                       
S0009919 00000090  AOF570I 07:05:12 : ISSUED "MVS F XCOM,STOP" FOR SUBSYSTEM XCOM - 094  
     094 00000090   PHASE IS SHUTNORM                                                    
S0155742 00000090  XCOMM0032I CANCEL   COMMAND EXECUTED FOR *                            
S0155742 00000090  XCOMM0198I XCOM NORMAL SHUTDOWN STARTED - ENDING SESSIONS             
S0155742 00000090  XCOMM0012I STOP     COMMAND PROCESSING SUCCESSFUL                     
*****

Around 7:10 am an immediate shutdown was issued:

*****
2024144 07:10:12.34 AWRK19RA 00000290  F XCOM,STOP,IMMED                                                         
2024144 07:10:12.34 S0155742 00000090  XCOMM0013I STOP,IMMED                                                     
2024144 07:10:12.34 S0155742 00000090  XCOMM0199I XCOM IMMEDIATE SHUTDOWN INITIATED                              
2024144 07:10:12.34 S0155742 00000090  XCOMM0012I STOP     COMMAND PROCESSING SUCCESSFUL                         
2024144 07:10:12.34 S0009919 00000090  AOF570I 07:10:12 : ISSUED "MVS F XCOM,STOP,IMMED" FOR SUBSYSTEM 925       
                         925 00000090   XCOM - PHASE IS SHUTNORM                                                 
2024144 07:10:12.34 S0155742 00000090  XCOMM0015I CBRAXCOM ACB CLOSED SUCCESSFULLY                               
2024144 07:10:12.34 S0155742 00000090  XCOMM0796I SHUTDOWN IN PROGRESS, TCP/IP REMOTE CONNECTIONS NO LONGER      
                                       AVAILABLE                                                                 
2024144 07:10:12.34 S0155742 00000090  XCOMM0808I SHUTDOWN IN PROGRESS, TCP/IP SSL REMOTE CONNECTIONS NO         
                                       LONGER AVAILABLE                                                          
2024144 07:10:12.34 S0155742 00000080  XCOMM0780E Txpi  810: Internal error: handle 0x301 for SERVER CLIENT      
                                       is not allocated.                                                         
2024144 07:10:12.34 S0155742 00000080  XCOMM0780E Txpi  215: Socket send error return value = 113                
2024144 07:10:12.34 S0155742 00000090  XCOMM0303I PSO SUBTASK TERMINATING NORMALLY                               
2024144 07:10:12.34 S0155742 00000090  XCOMM0038I PSO SUBTASK DETACHED SUCCESSFULLY                              
2024144 07:10:12.36 S0155742 00000080  XCOMM1168I PLEXQ LISTENER TASK STOPPING    

SYSTEM COMPLETION CODE=0C1  REASON CODE=00000001                
  TIME=07.10.12  SEQ=63120  CPU=0000  ASID=0173                         
 PSW AT TIME OF ERROR  078D2400   80000002  ILC 2  INTC 01             
   NO ACTIVE MODULE FOUND                                              
   NAME=UNKNOWN                                                        
   DATA AT PSW  00000000 - 00000000  00000000  00000000                
   AR/GR 0: 5FFFFFFF/00000000_00000000   1: 0101003D/00000000_1EE3D848 
         2: 00000000/00000000_1EE3D9A0   3: 00000000/00000000_1E352ADE 
         4: 00000000/00000000_00003E10   5: 00000000/00000000_1EDBEE48 
         6: 00000000/00000000_1EE40E64   7: 00000000/00000000_00000000 
         8: 00000000/00000000_00000000   9: 00000000/00000000_00000001 
         A: 00000000/00000000_00000000   B: 00000000/00000000_00000001 
         C: 00000000/00000000_1EDB03D0   D: 00000000/00000000_1EE3D7B0 
         E: 00000000/00000000_9E352996   F: 00000000/00000050_00000000 
 END OF SYMPTOM DUMP         
*****

Doing a "F XCOM,STOP" will wait for the transfer activity to complete before terminating which can cause a delay.
"F XCOM,STOP,IMMED" should NOT be used. It is an EMERGENCY response when a server is not going to terminate on its own. Also, if the "IMMED" option is used, abends should be expected, and appropriate actions should be taken by the operators or systems programmers to handle the situation.