NEC Storage Performance Monitor/Optimizer User Manual page 25

(1) Types of statistic information
iSM accumulates the following types of statistic information in statistic information history files.
(i) External I/O count
This is the number of input/output requests received by the disk array from the external in each measurement period.
The unit is the number of times.
(ii) External Average Response Time
This is the Average Response Time for the input/output requests received by the disk array from the external in each
measurement period. The unit is microsecond. This is calculated by measuring the total of the external response
time and external I/O count during the unit measurement period and dividing the former by the latter.
(iii) External Maximum Response Time
This is the maximum response time for the input/output requests received by the disk array from the external in each
measurement period. The unit is microsecond.
(iv) External Transfer Rate
This is the average Transfer Rate of the input/output process achieved in response to the input/output requests received
by the disk array from the external in each measurement period. The unit is kilobyte/second. 1 kilobyte is 1024
bytes. This is calculated by measuring the total of the amount of external data transfer during the unit measurement
period and dividing it by the time interval of the measurement period.
(v) Internal I/O Count
This is the number of input/output requests issued to the internal disk devices by the control device of the disk array in
each measurement period. The unit is the number of times.
(vi) Internal Average Response Time
This is the Average Response Time for the input/output requests issued to the internal disk devices by the control
device of the disk array in each measurement period. The unit is microsecond. This is calculated by measuring the
total of the internal response time and internal I/O count during the unit measurement period and dividing the former
by the latter.
(vii) Internal Maximum Response Time
This is the maximum response time for the input/output requests issued to the internal disk devices by the control
device of the disk array in each measurement period. The unit is microsecond.
(viii) Internal Transfer Rate
This is the average Transfer Rate of the input/output requests issued to the internal disk devices by the control device
of the disk array in each measurement period. The unit is kilobyte/second. 1 kilobyte is 1024 bytes. This is
calculated by measuring the total of the amount of internal data transfer during the unit measurement period and
dividing it by the time interval of the monitoring period.
(ix) Internal average Busy Ratio
For physical disk and RANK, the value indicates the rate of operation. Unit is percent [%]. The value is calculated
by measuring operating time physical disk and RANK, and by dividing the operating time by a time slot of measuring
segment.
A Busy Ratio of logical disk is found by dividing the Busy Ratio of RANK by the ratio of loads on the logical disk.
(x) Internal Operating Time
The value indicates the operating time of physical disk and RANK within a measurement time of unit. Unit is
Chapter 1 Overview of Performance Monitoring Function
I-19