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MA46475 - OSP-DB-OTHER FILE WITH AUX SPACE BECOMES DAMAGED.

 APAR (Authorized Program Analysis Report)

Abstract

OSP-DB-OTHER FILE WITH AUX SPACE BECOMES DAMAGED.

Error Description

File with AUX space becomes damaged.                            

Problem Summary

When a file contains large variable length fields (BLOB, CLOB,  
etc) and there is one or more jobs reading from the file at the
same time one or more jobs are inserting into the end of the    
file, it is possible that one of the reader jobs may detect a  
mismatch between the fixed length portion of the record and the
variable length portion of the record.  This occurs because, in
rare instances in the insert path, the code determines that it  
needs to extend an internal structure housing location          
information.  Unfortunately the serialization used when        
extending this structure is not sufficient enough to prevent a  
reader job from seeing the structure in flux, thus causing the  
mismatch.  This results in a read error, a 0600 5EED vlog, and  
the file being marked damaged.  Although in actually, if the    
read is tried again to the same record, it will be successful.  
                                                               
It should be noted that no data is lost or corrupted and all    
records can be read successfully and correctly once the internal
structure is no longer in flux.  The file is not actually      
damaged and was marked damage in error.                        

Problem Conclusion

This PTF enforces more strict serialization when these internal
structures are being extended so that NO other job or task will
see the structures while they are in flux, thus a reader job    
would neve find the structure in flux and would find the correct
VL data.                                                        
                                                               
As noted in the problem description When the structure is not in
flux, all reads are correct and successful.  The file was marked
damaged in error.  However, this PTF will NOT unmark the file.  
Service must be contacted to have the damage indication        
reversed.                                                      

Temporary Fix

                       *********                                
                       * HIPER *                                
                       *********                                

Comments

Circumvention


PTFs Available

R710 MF66372 PTF Cover Letter   1000
R720 MF63831 PTF Cover Letter   7290
R730 MF63832 PTF Cover Letter   7283

Affected Modules

         
         

Affected Publications

Summary Information

Status............................................ CLOSED PER
HIPER........................................... Yes
Component.................................. 9400DG3DB
Failing Module.......................... RCHMGR
Reported Release................... R710
Duplicate Of..............................




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Document information

More support for: i family

Software version: V7R1M0, V7R2M0, V7R3M0

Operating system(s): OS/400

Reference #: MA46475

Modified date: 18 July 2019