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122 Storage Management with DB2 for OS/390
the accounting report. Some additional information is calculated in this report, for
example, in Figure 45 it shows the average number of pages for each type of
prefetch read.
Figure 45. DB2 PM Statistics, Buffer Pool Read Operations Section
11.1.2.2 Log Activity
The log activity report gives detailed information about log I/O. Figure 46 on
page 123 shows a log activity section from a statistics report.
The block of lines identified by
A in Figure 46 indicate read access. The different
values indicate statistics for each possible source of log records. For performance
reasons, most of the reads should be satisfied from the output buffer: the archive
log should only be used for exceptional circumstances. Please refer to 10.5, “Log
Reads” on page 115 for details.
The block of lines identified by
B in Figure 46 indicates write access. This is
explained in 10.4, “Log Writes” on page 111.
BP4 READ OPERATIONS QUANTITY /MINUTE /THREAD /COMMIT
--------------------------- -------- ------- ------- -------
BPOOL HIT RATIO (%) 55.12
GETPAGE REQUEST 221.8K 6534.43 N/C 110.9K
GETPAGE REQUEST-SEQUENTIAL 18427.00 542.99 N/C 9213.50
GETPAGE REQUEST-RANDOM 203.3K 5991.43 N/C 101.7K
SYNCHRONOUS READS 613.00 18.06 N/C 306.50
SYNCHRON. READS-SEQUENTIAL 64.00 1.89 N/C 32.00
SYNCHRON. READS-RANDOM 549.00 16.18 N/C 274.50
GETPAGE PER SYN.READ-RANDOM 370.36
SEQUENTIAL PREFETCH REQUEST 577.00 17.00 N/C 288.50
SEQUENTIAL PREFETCH READS 577.00 17.00 N/C 288.50
PAGES READ VIA SEQ.PREFETCH 18440.00 543.38 N/C 9220.00
S.PRF.PAGES READ/S.PRF.READ 31.96
LIST PREFETCH REQUESTS 0.00 0.00 N/C 0.00
LIST PREFETCH READS 0.00 0.00 N/C 0.00
PAGES READ VIA LIST PREFTCH 0.00 0.00 N/C 0.00
L.PRF.PAGES READ/L.PRF.READ N/C
DYNAMIC PREFETCH REQUESTED 2515.00 74.11 N/C 1257.50
DYNAMIC PREFETCH READS 2515.00 74.11 N/C 1257.50
PAGES READ VIA DYN.PREFETCH 80470.00 2371.23 N/C 40.2K
D.PRF.PAGES READ/D.PRF.READ 32.00
PREF.DISABLED-NO BUFFER 0.00 0.00 N/C 0.00
PREF.DISABLED-NO READ ENG 0.00 0.00 N/C 0.00
SYNC.HPOOL READ 0.00 0.00 N/C 0.00
ASYNC.HPOOL READ 0.00 0.00 N/C 0.00
HPOOL READ FAILED 0.00 0.00 N/C 0.00
ASYN.DA.MOVER HPOOL READ-S 0.00 0.00 N/C 0.00
ASYN.DA.MOVER HPOOL READ-F 0.00 0.00 N/C 0.00
PAGE-INS REQUIRED FOR READ 59.00 1.74 N/C 29.50