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The statistic information accumulation function described above accumulates statistic information collected in every
logging Interval in statistic information history file. If statistic information collected in relatively short intervals is
accumulated in the long term, the amount of data in the statistic information history file will become enormous and
eventually exhaust the free disk space.
For saving disk space, the accumulated statistic data is summarized into the information of a period longer than the logging
interval, reducing amount of information included in a file, downsizing the data. This function is called summarizing
statistic information. The information after summarizing is output to statistic information summarized file.
When you want to accumulate statistic information in the long term, you can save the disk space by using this function as
required to summarize statistic information and deleting the statistic information originally accumulated. For information
on how to estimate the size of a statistic information summarized file, refer to Appendix D "Estimation of NEC Storage
PerformanceMonitor File Size" of this manual.
(1) Summarizing basic statistic information
The summarizing function statistic information summarizes all basic information stored (refer to table 1-3), and
outputs the information to a statistic information summarized file. The following describes basic statistic
information after summarizing.
For statistic information regarding I/O count, the I/O counts within all the measurement periods contained in the
period of summarizing are accumulated, and the result is the I/O count of the period of summarizing.
Statistic information of average response time: On the basis of all average response times and I/O counts within
applicable summarizing segments, total response time and total I/O count are found. Average response time is
calculated by dividing the former by the latter.
For statistic information regarding maximum response time, the maximum value is taken from the maximum
response times within all the measurement periods contained in the period of summarizing, and it is the maximum
response time of the period of summarizing.
Statistic information of transfer rate: On the basis of all transfer rates within applicable summarizing segments, total
transfer length is found. A transfer rate of the summarizing segment is calculated by dividing the total transfer
length by the measurement time of the summarizing segment.
Statistic information of Busy Ratio: All busy time within applicable summarizing segments is accumulated.
Average Busy Ratio of the summarizing segment is calculated by dividing the total busy time by the measurement
time of the summarizing segment.
For statistic information regarding operating time, the operating time within all the measurement periods contained
in the period of summarizing are accumulated and the result is the operating time of the period of summarizing.
(2) Inserting extended statistic information
For allowing reference to the fluctuation width of statistic information even after summarizing, extension of statistic
information is calculated in addition to the summarized basic statistic information and stored in the summarized
statistic information file. The extension of statistic information includes the following types.
Chapter 1 Overview of Performance Monitoring Function
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