NEC Storage Performance Monitor/Optimizer User Manual page 22

Chapter 1 Overview of Performance Monitoring Function
If accumulation start and stop operations are repeated without shut down and start up of the iSM server, the file serial
number is not assigned or incremented and accumulation of statistic information to the same file continues.
For information on how to estimate the size of a statistic information history file, refer to Appendix D "Estimation of
NEC Storage PerformanceMonitor File Size".
The period of reading statistic information is called the logging Interval. The user can specify the logging Interval from 1
minute to 60 minutes at environment definition of the iSM server. The logging Interval cannot be changed while the iSM
server is operating. To change the logging Interval, you must terminate the iSM server.
The accumulating processes of statistic information limits the number of times for collecting statistic information within a
specified time, in order not to affect input/output process from the business host. Therefore, too many disk array
components may prevent collecting statistic information within a specified logging interval, and may disable starting of the
data accumulation process. In such a case, specifying the automatic adjustment of logging interval in the environment
definition of the iSM server adjusts the intervals appropriately, and prevents such failures in accumulating processes.
When a logging interval is automatically adjusted, a message notifies the adjustment.
The monitored disk arrays collect various types of statistic information by component/load type in the unit of summarizing.
From the statistic information, iSM reads the statistic information of the types shown in Table 1-3 and accumulates the time
changes in the statistic information history file. Such statistic information is called basic statistic information.
iSM also records information required for the following purposes in the statistic information history file.
Component information required to interpret accumulated statistic information
Name tags used for displaying the results of analysis
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