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APAR NUMBER: PJ31135 PRODUCT: TPF4 FUNCTIONAL AREA: CONTINUOUS DATA COLLECTION (CDC) SHIPPED IN PUT: 20 ABSTRACT: With Continuous Data Collection (CDC) running, negative values for tape information could be generated. APAR CONTENTS: FEATURE TYPE STATUS NAME Base C Changed source/rt/base/cdcp.c PREREQUISITE APARS: To be applied in order listed. Base C Changed source/rt/base/cdcp.c PJ27095(12) PJ27775(15) PJ28097(15) PJ29925(19) PJ30137(19) PJ30215(20) PJ30233(20) PJ30253(20) PJ30251(20) PJ30465(20) PJ30503(20) PJ30701(20) PJ30589(20) PJ30610(20) PJ30946(20) PJ31004(20) COMMENTS: There are occasions when CDC is running where negative values for tape "writes" and "bytes written" are generated. These negative values have been observed when querying the CDC DB2 database for tape information for a time span during which a tape switch occurred. SOLUTION: The TPF Tape Status Table (TSTB) contains entry for all tapes configured on a system. Each entry in that table has an unsigned 4 byte field (CPMTC0) representing the number of bytes written to that entry. It also contains an unsigned 2 byte field (CPMTC1) representing the number of writes to the tape. These fields are assigned on a tape mod basis and do not get reset when a tape is swapped (i.e. these counts belong to a tape name, not the tape name AND device number). In order to maintain correct counts, CDC will make sure that each tape entry it collects will have the same tape name and device number for at least two intervals before adding the tape to the collection and storing its information. Also, the collector was treating CPMTC1 field (an unsigned short) as an unsigned integer when trying to account for counter roll-over. This has been corrected and field is now treated as an unsigned short during these calculations. It is necessary to point out that all the of the numbers in the CDC collector are unsigned. If a customer is using DB2, it does not have unsigned data type support. This entails that in DB2, any number higher than 2^31 will be represented as a negative value. That does not mean that the number is incorrect, DB2 just stores it as such. The correct representation of the value will be handled at the presentation layer (i.e. the CDC client). If a customer has any reporting applications that runs off of this data, it should be accounted for in their application as well. DEPENDENCIES SEGMENTS TO BE ASSEMBLED OR COMPILED: None. SEGMENTS TO BE LINK EDITED: cdcp40.exe (Shipped in Tar File) 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 PJ31135
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