MFE SCF: SRDF/STAR MSC activation got OBT SEL failed RC 8 and then disabled

Summary: One MSC group in the GDDR C-system was performing an activation, received message SCF15C4W, OBT SEL failed RC 8, and then disabled.

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Symptoms

One MSC group in the GDDR C-system was performing activation, received message SCF15C4W, OBT SEL failed RC 8, and then disabled. An example is given below.

00.19.52 STC02874  SCF1335I MSC - GROUP=mscgrp1                   MOTHER TASK STARTED                                               
00.19.52 STC02874  SCF1319I MSC - SET TO ADCOPY-DISK ON SRDFA DROP                                                                  
00.19.52 STC02874  SCF1568I MSC - GROUP=mscgrp1                   WEIGHT FACTOR =  0                                                
00.19.52 STC02874  SCF1328I MSC - GROUP=mscgrp1                   (080B4,007F) SRDFA ACTIVE                                         
00.19.52 STC02874  SCF1569I MSC - GROUP=mscgrp1                   STEAL LOCK AFTER =  10 MIN(S)                                     
00.19.52 STC02874  SCF1326I MSC - GROUP=mscgrp1                   (080B4,007F) SERIAL = 000197600361                                
00.19.52 STC02874  SCF1426I MSC - GROUP=mscgrp1                   (080B4,007F) GETTING SEL LOCKS                                    
00.19.52 STC02874  SCF15C4W MSC - GROUP=mscgrp1                   (080B4,007F) R1 OBT SEL failed for LOCKID X'02A6B248', RC 8       
00.19.52 STC02874  SCF1435I MSC - GROUP=mscgrp1                   (080B4,007F) FREEING SEL LOCKS                                    
00.19.53 STC02874  SCF1426I MSC - GROUP=mscgrp1                   (080B4,007F) GETTING SEL LOCKS                                    
00.19.53 STC02874  SCF15C4W MSC - GROUP=mscgrp1                   (080B4,007F) R1 OBT SEL failed for LOCKID X'02A6B248', RC 8       
00.19.53 STC02874  SCF1435I MSC - GROUP=mscgrp1                   (080B4,007F) FREEING SEL LOCKS                                    
00.19.54 STC02874  SCF1426I MSC - GROUP=mscgrp1                   (080B4,007F) GETTING SEL LOCKS   
……
00.20.22 STC02874  SCF1437I MSC - GROUP=mscgrp1                   NOT ABLE TO OBTAIN ALL SEL LOCKS        
……
00.21.22 STC02874  SCF1479I MSC - GROUP=mscgrp1                   NOT ABLE TO OBTAIN ALL STAR SEL LOCKS        
00.21.23 STC02874  SCF1435I MSC - GROUP=mscgrp1                   (080B4,007F) FREEING SEL LOCKS               
00.21.23 STC02874  SCF1480I MSC - GROUP=mscgrp1                   (080B4,007E) FREEING STAR SEL LOCKS          
00.21.28 STC02874  SCF1333I MSC - GROUP=mscgrp1                   MOTHER TASK ENDED                            
00.21.28 STC02874  SCF15AAI MSC - GROUP=mscgrp1                   DISABLE complete

Cause

Running MSC with high availability without sharing system enqueues, the storage system level locks are required to be obtained from the local and remote DASD subsystems. The issue occurred due to OBT SEL lock conflict, another MSC instance held the same local and remote locks. Both instances are using the same DASD subsystems.

GDDR allows C-system multitenancy, and in the GDDR manual, it mentions below: 

'NOTE: C-instances can share Dell storage systems. However, MSC activation cannot occur simultaneously in two or more instances if they share a storage system. In this case, only one of the activations succeeds; the others have to be re-driven.'

Resolution

To recover from the above issue, perform an MSC REFRESH and run the GLOBAL,PARM_REFRESH command after the first MSC activation completes.

To avoid this issue, if using C-system multitenancy, do not simultaneously run MSC activation for multiple instances.

Affected Products

Mainframe Enablers
Article Properties
Article Number: 000226071
Article Type: Solution
Last Modified: 30 Aug 2024
Version:  2
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