HP Capacity Advisor 7.2 User Guide

(increased by 100%, or twice the current size) from their utilization during the selected reporting
period.
Large values for relative headroom
The scenario comparison report provides indicators of relative headroom for CPU and memory
use for two – four selected scenarios.
This report limits the relative headroom that can be displayed to a maximum of >1000%, which
means the corresponding utilization could be increased at least 10 times its current value and the
utilization limits for that resource would not be exceeded. Values in this range can seem quite
large, and they are. Normally, values in this range would only occur on a vastly under-utilized
system.
Interpreting the star rating given by the HP Smart Solver
When using the Smart Solver to find a plan to convert physical systems to virtual machines, consider
the following factors that can adversely affect the Smart Solver results.
• The addition of a virtualization overhead multiplier to a VM will often reduce the number of
stars for that workload by one or two stars.
• The clock speed of the VM host may be slower than the original physical system. Work that
was done by one core at 2.6 GHz, may require two cores when placed on 2.1 GHz VM
host.
You can avoid having the Smart Solver produce inaccurate or useless results by re-sizing your
systems before running the Smart Solver. If either of the above conditions exist in your situation,
consider increasing the number of cores on your simulated physical systems before running the
Smart Solver. (Select What-if Actions→Edit System... on the System tab on the Edit Scenario screen.)
If you change the number of cores from one to two before consolidating, for example, the resulting
virtual machines will have enough cores to cover the virtualization overhead or a slower VM host.
Resizing the virtual machines after running the Smart Solver can be less effort, as you only have
to resize the VMs that have fewer stars than your desired goal. After adding more cores to the
VMs for which CPU resources are too tight, you can rerun Smart Solver to balance the load on the
VM hosts to improve the solution a bit more.
TIP: Use a Scenario comparison report to compare the headroom stars rating for saved scenarios.
Missing or invalid data
Data collected by Capacity Advisor is used in the scenarios you create and manipulate. During
an interval when no data was collected, the data is considered missing (data may not have been
collected, for example, because a system was down during data collection). Invalidated (or invalid)
data is data that you have marked as invalid.
For each metric about a system or workload, if a significant amount of data is missing or invalid,
the metric is followed by asterisks with the following meaning:
• [blank] : 91% to 100% of data is valid.
• * : 51% to 90% of data is valid.
• ** : 11% to 50% of data is valid.
• *** : Less than 10% of data is valid.
• N/A: There is no valid data.
Thus, metrics asterisks are considered useful and reliable for analysis.
Measuring and analyzing resource utilization 27