HP Capacity Advisor 7.2 User Guide

choose, select Configure→Edit Network and Disk I/O Capacity... from the Visualization tab in
Matrix Operating Environment.
Disk I/O
The maximum capacity for disk I/O defaults to the high-water mark (that is, the maximum observed
or collected value) for disk I/O. However, to set the upper bound to a value you choose, select
Configure→Edit Network and Disk I/O Capacity... from the Visualization tab in Matrix Operating
Environment.
Power
Expected maximum and minimum power values for systems and workloads are computed using
the CPU and power utilization data collected from HP Insight Control power management. However,
these values can also be set manually from the Matrix OE visualization menu bar (select
Configure→Calibrate Power (All Selected Systems)...) for specified systems; or from the Capacity
Advisor Edit Scenario: System tab menu bar (select Edit→Calibrate Power (All Selected Systems)...)
for a specific scenario.
Measuring and analyzing resource utilization
In using Capacity Advisor, it is helpful to understand how the tool approaches sampling and data
analysis, and the user-provided information that affects these.
Peaks and sums
Measuring utilization of computing resources is more complex than simply determining the maximum
memory or processor utilization.
Sum of peaks
An old standby in capacity planning is to simply take the peak of the two loads and use that to
determine the maximum required capacity; this is the “sum of peaks”. While this will definitely
provide a robust solution, it does not take into account the timing of the peak of the loads and may
end up planning for more capacity than is actually used.
Peak of sums
A more efficient planning solution, which is easily accomplished using Capacity Advisor, takes
into account the timing of the maximum utilization peaks in the individual loads. By adding together
utilization at each measured interval and then taking the maximum of the resulting time sequence,
a more accurate measure of the required maximum resource can be determined. This can lead to
cost savings when planning the resources required to consolidate loads onto new or existing
servers.
Sampling interval
Where used, the Utilization Provider runs on each monitored system to collect information on
resource utilization. At the CPU-clock cycle level, a processor is either busy or idle. For Capacity
Advisor, the average utilization for each five-minute (300 seconds) interval is stored. Therefore,
peaks lasting less than five minutes are not visible.
Because each data point is the average of the five preceding minutes of values, this averaging
tends to flatten the graphs, particularly when compared with real-time graphs in which each data
point is the average of values from the 15 preceding seconds.
For data collected using an agentless solution on Windows managed systems, collection intervals
can vary depending on values that you set and the number of machines in the collection.
Headroom
Headroom is the difference between the observed utilization on a system and the maximum available
capacity. That is, the headroom of a system is the amount of additional capacity that can be used
without violating the utilization limits of the applications running on that system. For example, if
Measuring and analyzing resource utilization 25