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Case Study 149
12.2.1.1 Device Activity Report Analysis
The RMF report analysis is based on the LCU level and Storage Group level
device activity reports. Figure 68 on page 149 shows the extracted summary
lines. The Storage Group level line is the average combination of LCUs 46-48 and
4A-4D activities, as the detail volume level display shows (refer to Figure 49 on
page 127 as an example). The other information to review is:
• DEVICE ACTIVITY RATE is spread across both LCUs and RVAs inside the
Storage Group, which indicates an allocation controlled environment. The
level of activity is 90.959.
• AVG RESP TIME is 31 ms.
• AVG IOSQ TIME is 1 ms, which also leads to a controlled environment.
• AVG PEND TIME is 0.2 ms, not an issue.
• AVG DISC TIME is 7.1 ms, which is quite high but lower than the connect time.
This requires further analysis.
• AVG CONN TIME is 22.7 ms, which indicates heavy transfers. This
information matches the DB2 PM overview of 32 pages, each consisting of
one 4K CI, plus some overhead. The accuracy of this estimate is based on
supposed homogeneous allocation parameters in the same Storage Group.
From the CONN time and ACTIVITY rate, the path demand is deduced thus:
( ( 90.959 x 22.7) / 1000 ) x 100 = 206.5 % of a path demand
This Storage Group level device activity report is only for one LPAR. Several
LPAR reports should be consolidated (with the spreadsheets) to get the global
Storage Group demand in a data sharing environment. The case study is for only
one LPAR. A more complex situation would be several LPARs spead across
different CPCs, with EMIF shared channels.
Figure 68. Case Study RMF Direct Access Device Activity Report Extract
12.2.1.2 I/O Queuing Activity Report Analysis
Figure 69 on page 150 displays an extract of this report, which enumerates the
CHANNEL PATH hexadecimal identifications for each LCU:
DIRECT ACCESS DEVICE ACTIVITY
OS/390 SYSTEM ID QP02 START 02/12/1999-15.05.39 INTERVAL 000.38.01
REL. 02.06.00 RPT VERSION 2.6.0 END 02/12/1999-15.43.41 CYCLE 1.000 SECONDS
( RMF report extract )
DEVICE AVG AVG AVG AVG AVG AVG AVG AVG % % % AVG % %
STORAGE DEV DEVICE VOLUME LCU ACTIVITY RESP IOSQ DPB CUB DB PEND DISC CONN DEV DEV DEV NUMBER ANY MT
GROUP NUM TYPE SERIAL RATE TIME TIME DLY DLY DLY TIME TIME TIME CONN UTIL RESV ALLOC ALLOC PEND
LCU 0046 15.778 32 0 0.0 0.0 0.0 0.2 7.1 24.5 0.60 0.78 0.0 15.0 100.0 0.0
LCU 0047 8.752 33 2 0.0 0.0 0.0 0.2 6.7 24.7 0.34 0.43 0.0 14.0 100.0 0.0
LCU 0048 14.145 27 1 0.0 0.0 0.0 0.2 5.4 20.6 0.45 0.57 0.0 11.0 100.0 0.0
LCU 0049 7.923 32 0 0.0 0.0 0.0 0.2 7.0 24.7 0.31 0.39 0.0 19.0 100.0 0.0
LCU 004A 3.721 34 0 0.0 0.0 0.0 0.2 9.3 24.2 0.14 0.20 0.0 3.0 100.0 0.0
LCU 004B 14.431 26 2 0.0 0.0 0.0 0.2 6.3 17.8 0.40 0.54 0.0 4.0 100.0 0.0
LCU 004C 14.540 35 0 0.0 0.0 0.0 0.2 9.1 25.1 0.57 0.78 0.0 5.0 100.0 0.0
LCU 004D 11.668 30 0 0.0 0.0 0.0 0.2 7.6 22.3 0.41 0.55 0.0 7.0 100.0 0.0
LCU 0055 6.963 3 0 0.0 0.0 0.0 0.4 0.1 2.6 0.06 0.06 0.0 299 100.0 0.0
RVA1 SG 90.959 31 1 0.0 0.0 0.0 0.2 7.1 22.7 0.40 0.53 0.0 78.0 100.0 0.0