IBM 5695-DF1 manual Device Activity Report Analysis, 12.2.1.2 I/O Queuing Activity Report Analysis

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.

					D I R E C T A C C E S S D E V I C E A C T I V I T Y
	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

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:

Case Study 149