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APAR NUMBER:  PJ31704                         
PRODUCT:  TPF4
FUNCTIONAL AREA:  CONTINUOUS DATA COLLECTION (CDC)
SHIPPED IN PUT:  21
 

ABSTRACT:
If CDC uses TPFDF to store data, then data corruption may
occur. The corruption can occur if a chained block becomes
empty in file IRC1DF and recoup is subsequently run.
 
APAR CONTENTS:
FEATURE   TYPE                STATUS    NAME                              
Base      Assembler           Changed   source/rt/base/uf1t.asm
 
PREREQUISITE APARS:  To be applied in order listed.
Base      Assembler           Changed   source/rt/base/uf1t.asm
 PJ29925(19)  PJ30137(19)  PJ30701(20)  
 
COMMENTS:
CDC has an optional feature that writes CDC data to a TPFDF
file. TPFDF file IRC1DF is the detail file for the CDC data.
IRC1DF is indexed by a B+Tree index. Currently, the DBDEF
statements for IRC1DF do not include DELEMPTY=YES and
FULLBCH=YES parameters. Without these DBDEF parameters, when a
chained block becomes empty the reference to the empty block is
removed from the B+Tree index, but the reference remains in the
forward chain of the detail file. The DBDEFs for IRC1DF are
coded to use multiple ECBs to recoup IRC1DF using the B+Tree
index. So recoup will report the empty chain block as a lost
address. If the lost address is made available, data corruption
can occur because the forward chain in IRC1DF still references
this pool file.
 

SOLUTION:
Updated the DBDEFs for IRC1DF in segment uf1t.asm to use
parameters DELEMPTY=YES and FULLBCH=YES. With these parameters,
when chained blocks become empty, they will be released and the
references will be removed from the forward chain of IRC1DF.
This will avoid corrupting IRC1DF because there will no longer
be empty blocks in the forward chain that can be reported as
"lost addresses" and possibly returned to available pool.
 
 

DEPENDENCIES
 
SEGMENTS TO BE ASSEMBLED OR COMPILED:
None.
 
SEGMENTS TO BE LINK EDITED:
None.
 
COREQS:
None.
 

MIGRATION CONSIDERATIONS:
None.
 
UPDATED INFORMATION UNITS:
None.
 
See your IBM representative if you need additional information.
 

DOWNLOAD INSTRUCTIONS:
http://www.ibm.com/software/htp/tpf/pages/maint.htm

 
-- END APAR PJ31704
      




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