The Historical Observations and Growth Rate Reports for SIO counts are shown in Figure 5-8. Like the Channel Utilization Reports, these show that the I/O load is increasing slightly over the long term, but with a large amount of recent variability. By comparing long- and short-term trends between related variables, you can often see changes in the fundamental behavior of the workload. The growth rates shown in the SIO Count Report are generally smaller than the corresponding growth rates in channel utilization. This may mean that the average amount of data transferred by an I/O is increasing over time. Does this indicate that larger block sizes are being used? A change in the character of the workload certainly affects the interpretation of the forecasts. A positive long-term growth rate does not necessarily imply that each of the observations in the historical series has been steadily increasing, but only that the long term-trend between the first and last observation is positive (see channel 1 in Figure 5-8).
+----------------------------------------------------------------------------------------------------------------------------------+ |SYSID: TSO1| | | | EXTENDED EXAMPLE --- MONTHLY HISTORICAL OBSERVATIONS | |ZONE: 1 | | |-----------+----------------------------------------------------------------------------------------------------------------------| | | CHANNEL 1 | CHANNEL 2 | CHANNEL 3 | CHANNEL 4 | CHANNEL 5 | | | | MONTH | SIO COUNT | SIO COUNT | SIO COUNT | SIO COUNT | SIO COUNT | | | |-----------+----------------+----------------+----------------+----------------+----------------+----------------+----------------+ | SEP 97 | 10283160.0 | 12621388.0 | 16971048.0 | 3640411.0 | 11882418.0 | | | | OCT 97 | 11306966.0 | 13861055.0 | 18385386.0 | 3822387.0 | 12860633.0 | | | | NOV 97 | 11414859.0 | 11717108.0 | 16663774.0 | 4338143.0 | 11743581.0 | | | | DEC 97 | 9976870.0 | 12327566.0 | 16800745.0 | 5247391.0 | 12510012.0 | | | | JAN 98 | 10611907.0 | 11156555.0 | 16185623.0 | 4257223.0 | 12071368.0 | | | | FEB 98 | 10960937.0 | 12830799.0 | 15257229.0 | 5641456.0 | 12076524.0 | | | | MAR 98 | 10025924.0 | 12843967.0 | 13669835.0 | 5318293.0 | 12186976.0 | | | | APR 98 | 9870709.0 | 13093325.0 | 14904987.0 | 5033416.0 | 14355185.0 | | | | MAY 98 | 8851487.0 | 11399322.0 | 13645679.0 | 4494512.0 | 15011392.0 | | | | JUN 98 | 10545954.0 | 12099310.0 | 14443173.0 | 5437664.0 | 17176448.0 | | | | JUL 98 | 14139601.0 | 13436249.0 | 15858031.0 | 6582489.0 | 17421158.0 | | | | AUG 98 | 14220067.0 | 17448773.0 | 14690555.0 | 6879567.0 | 18042957.0 | | | +----------------------------------------------------------------------------------------------------------------------------------+ +----------------------------------------------------------------------------------------------------------------------------------+ |SYSID: TSO1| | | | EXTENDED EXAMPLE --- GROWTH RATE PER MONTH | |ZONE: 1 | | |-----------+----------------------------------------------------------------------------------------------------------------------| | | CHANNEL 1 | CHANNEL 2 | CHANNEL 3 | CHANNEL 4 | CHANNEL 5 | | | | INTERVAL | SIO COUNT | SIO COUNT | SIO COUNT | SIO COUNT | SIO COUNT | | | |-----------+----------------+----------------+----------------+----------------+----------------+----------------+----------------+ | 11 MOS | 2.99 % | 2.99 % | -1.30 % | 5.96 % | 3.87 % | | | | LAST MO | 0.57 % | 29.86 % | -7.36 % | 4.51 % | 3.57 % | | | +----------------------------------------------------------------------------------------------------------------------------------+
Figure 5-8. Extended Example Historical Observations and Growth Rate Reports: SIO Counts
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