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RID POOL - HWM RID Pool Blocks statistic review


Article ID: 225513


Updated On:


SYSVIEW Performance Management Option for DB2 for z/OS Database Management for DB2 for z/OS - SQL Performance Suite


The help field for HWM RID Pool Blocks in the following panel is defined as

Menu  Print  Tools  Help    CA SYSVIEW for Db2
R/SYSLPRF       List Prefetch / RID Pool 
RID POOL                        %MAXRBLK 
  RID Pool Current Blks       2      0.0 
  HWM RID Pool Blocks     35551    113.8 
  StIn HWM RID Blocks         5      0.0 
  RID Blks in Wrkfl Stg       0          
  HWM RID Blks in Wrkfl    1460          
  RID Failed RDS Limit        1          
  RID Failed DM Limit         0          
  RID Failed No Storage       0          
  RID Failed Processes        0          
  RID Overflow - Stg          0          
  RID Overflow - Limit        0          
  RID Interrupt - Stg         0          
  RID Interrupt - Limit       0          
  RID Multi-Index Skipd       2          

HWM RID Pool Blocks Field Level Help            
Max RID list blocks used:   
This field shows the maximum number of RID Pool blocks that have been allocated.  RID blocks are 4K pages used by DB2 to hold record IDs (RIDs) during multiple  index or List Prefetch processing. DB2 will stop allocating RID blocks when the size of the RID pool  reaches 50 percent       of the total size of the bufferpool (all pools).         
IQL Name:                 
DB2 Name: QISTRHIG        

How HWM RID Pool Blocks field value/percentage is calculated? The purpose is a better understanding to adjust warning threshold specifically for MAXRBLK value of 1000000 in DSNZPARM



Release : 20.0

Component : CA SYSVIEW Performance Management Option for DB2 for z/OS


SYSVIEW Performance Management Option for DB2 for z/OS The 'HWM RID Pool Blocks' shows the value of IQL field RIDLIST-MAX-BLOCKS, corresponding DB2 name:QISTRHIG=>" HIGHEST NUMBER OF RID BLOKS IN USE AT ANY ONE TIME SINCE DB2 STARTUP TIME". The adjacent percentage field is computed as(RIDLIST-MAX-BLOCKS/CURR-STATS1.MAX-RIDBLK-ALLOWED);Corresponding DB2 name  of IQL CURR-STATS1.MAX-RIDBLK-ALLOWED:Q3MXRBLK=> MAXIMUM NUMBER OF RID BLOCKS ALLOWED AT ANY TIME". You set "Maximum RID Pool Storage in kilobytes" via MAXRBLK in DSNZPARM. If MAXRBLK is set to 1000000, then the maximum allowed RID storage blocks(32k) is 31250. So if RIDLIST-MAX-BLOCKS is 35551 and CURR-STATS1.MAX-RIDBLK-ALLOWED is 31250; then the percentage would be 113.8, which is what is displayed in SYSLPRF IDB2 report.