Why after Datacom DEFRAG IXX did percent full continued to decrease?
Article ID: 201944
Updated On:
Products
Issue/Introduction
After running DEFRAG to reorganize the index and free up deleted space to my CA-11 base 601, the DATA AREA SPACE UTILIZATION REPORT also known as DBUTLTY "TYPE A" report (DBUTLTY with REPORT AREA=CXX,DBID=601,TYPE=A) decreased the percent full from 96% to 46%.
Then, a rerun of the TYPE A report several minutes later showed the percent continued to decrease to 2%.
Why did the percent continue to decrease with no additional DEFRAG?
After the DEFRAG, the TYPE A report showed 46% IXX percent full:
DATACOM/AD DATA AREA SPACE UTILIZATION REPORT
-AREA DATA TOTAL TOTAL TOTAL USED PERCENT PARTIALLY AREA REUSE
NAME BASE TRACKS RECORDS BLOCKS BLOCKS FULL MAX EMPTY BLKS OPTION
CXX 250 N/A 3,000 258 8 8 N/A N/A
IXX 601 16,500 N/A 198,000 92,673 46 96 N/A N/A
DSN 601 11,250 271,850 78,750 6,982 8 9 261 RANDOM
JHF 601 1,500 0 10,500 2 0 0 0 RANDOM
JOB 601 2,475 5,471 17,325 344 1 1 1 RANDOM
STP 601 2,475 27,352 17,325 601 3 3 103 RANDOM
Then, TYPE A report showed the followed several minutes later showed 2% IXX percent full:
DATACOM/AD DATA AREA SPACE UTILIZATION REPORT
-AREA DATA TOTAL TOTAL TOTAL USED PERCENT PARTIALLY AREA REUSE
NAME BASE TRACKS RECORDS BLOCKS BLOCKS FULL MAX EMPTY BLKS OPTION
CXX 250 N/A 3,000 258 8 8 N/A N/A
IXX 601 16,500 N/A 198,000 5,001 2 96 N/A N/A
DSN 601 11,250 271,850 78,750 6,981 8 9 261 RANDOM
JHF 601 1,500 0 10,500 2 0 0 0 RANDOM
JOB 601 2,475 5,471 17,325 344 1 1 1 RANDOM
STP 601 2,475 27,352 17,325 601 3 3 103 RANDOM
Environment
Datacom
Datacom/DB
Datacom/AD
15.1
15.0
Resolution
All index blocks deleted when running a DEFRAG are put on the Index Queue and each block will show up as truly deleted in the IXX report after the index queue processes it.
DEFRAG (Defragment Index)
MUF EOF report provides statistics "REQUEST COMPLETION TASKS" related to index queue processing.
COMM EOJ (End MUF Processing)
Also, X_DEFRAG_DELAY_QUEUE console or startup option allows you to throttle the index queue processing.
"When mass maintenance, especially deletes, to a data area adds very large numbers of blocks to the index queue, it might be beneficial to throttle DEFRAG processing."
X_DEFRAG_DELAY_QUEUE can slow the DEFRAG down so it does not flood the queue, but it is not recommended for situations where the queue finished its processing.
Additional Information
This is working as designed and had been provided as enhancement to Datacom.
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