HP XPWatch and HP XPSketch Reference Guide

D Comparing LDEV response time metrics in HP XP7
Performance Advisor and HP XPWatch
Maximum values of LDEV response time in HP XP7 Performance Advisor
and HP XPWatch
The maximum values of LDEV response time in XP7 Performance Advisor cannot be compared with
the response time values in HP XPWatch because HP XP7 Performance Advisor displays the I/O
response time as separate metrics for read and write, respectively.
HP XP7 Performance Advisor also displays the maximum and average values for LDEV response
time for reads and writes separately. The maximum values of the read and write response are
displayed within an interval of 30 seconds.
However, HP XPWatch does not display any related metric for the maximum value of read or write
response.
Average values of LDEV response time in HP XP7 Performance Advisor
and HP XPWatch
You can calculate the Average Read Response time and Average Write Response time using the
following formulae:
Average read response time
Front–end read response time over the collection interval / total front–end reads
Average write response time
Front-end write response time over the collection interval / total front–end writes
Because HP XPWatch displays the cumulative LDEV response time (that is, both reads and writes
combined) a direct comparison of the average values of LDEV response time in HP XP7 Performance
Advisor and HP XPWatch is not allowed.
68 Comparing LDEV response time metrics in HP XP7 Performance Advisor and HP XPWatch