Filter
Top Products
144 Storage Management with DB2 for OS/390
Figure 61. DB2 PM Statistics, Global DDF Activity Section
12.1.2 Data Access
The next step of this analysis is the examination of the buffer pools to establish
the pattern of data access. The accounting report shows that the following buffer
pools are being used:
BP0 System table and index spaces
BP2 User table spaces
BP4 User index spaces
BP5 Work DB table spaces
BP0 contains little data which is all in the buffer pool; this buffer pool contains the
DB2 Catalog and Directory. BP5 is another special case; it contains the work DB.
Both BP2 and BP4 contain interesting data. The corresponding sections from the
accounting report are in Figure 62 on page 144 and in Figure 63 on page 145.
The query accesses 5.8 million pages in BP2 (
A) and 0.3 million pages in BP4
(
F). No data is updated in either buffer pool.
In buffer pool BP2, 18796 pages (
B) are read synchronously and 5.8 million
pages (
E) are read with prefetch operations. The prefetch operations are
sequential prefetch (
C) and dynamic prefetch (D). The total is 186060 prefetches
that read 5795249 pages, an average of 31.15 pages per prefetch.
Figure 62. DB2 PM Accounting, BP2 Section
GLOBAL DDF ACTIVITY QUANTITY /MINUTE /THREAD /COMMIT
--------------------------- -------- ------- ------- -------
DBAT QUEUED-MAXIMUM ACTIVE N/P N/P N/P N/A
CONV.DEALLOC-MAX.CONNECTED N/P N/P N/P N/A
INACTIVE DBATS - CURRENTLY N/P N/A N/A N/A
INACTIVE DBATS - HWM N/P N/A N/A N/A
ACTIVE DBATS - CURRENTLY N/P N/A N/A N/A
ACTIVE DBATS - HWM N/P N/A N/A N/A
TOTAL DBATS - HWM N/P N/A N/A N/A
COLD START CONNECTIONS N/P N/P N/P N/P
WARM START CONNECTIONS N/P N/P N/P N/P
RESYNCHRONIZATION ATTEMPTED N/P N/P N/P N/P
RESYNCHRONIZATION SUCCEEDED N/P N/P N/P N/P
BP2 TOTAL
--------------------- --------
BPOOL HIT RATIO (%) 0
GETPAGES 5835348 A
BUFFER UPDATES 0
SYNCHRONOUS WRITE 0
SYNCHRONOUS READ 18796 B
SEQ. PREFETCH REQS 163939 C
LIST PREFETCH REQS 0
DYN. PREFETCH REQS 22121 D
PAGES READ ASYNCHR. 5795249 E