Skip to: Abstract | Comments | Solution | Migration | Download

APAR NUMBER:  PJ31765                         
PRODUCT:  z/TPF
FUNCTIONAL AREA:  CONTINUOUS DATA COLLECTION (CDC)
SHIPPED IN PUT:  4
 

ABSTRACT:
If CDC uses z/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.
 
PACKAGE CONTENTS:
Source Segments:
(C) base/rt/uf1t.asm
 
Object Only Binaries:
None.
 
Configuration Independent Binaries:
None.
 
Support Files:
None.
 
OTHER BINARIES TO BUILD:
(C) <sys>/obj/uf1t.o
(C) <sys>/load/UF1T.so
 
PREREQUISITE APARS IN APPLICATION ORDER:
base/rt/uf1t.asm
PJ30362(1) PJ30742(2) 
<sys>/obj/uf1t.o
PK06657(1) PJ30362(1) PJ30742(2) 
<sys>/load/UF1T.so
PK06657(1) PJ30362(1) PJ30742(2) 
 

COMMENTS:
CDC has an optional feature that writes CDC data to a z/TPFDF
file. z/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.
 
COREQS:
PK25978
 

MIGRATION CONSIDERATIONS:
None.
 
BUILD COMMANDS AND INSTRUCTIONS:
#maketpf commands for linux
maketpf -f UF1T uf1t.o
maketpf UF1T link
 
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
 
APAR URL:
http://www.ibm.com/software/htp/tpf/ztpfmaint/put4/PJ31765.htm
APAR Package