HP Matrix Operating Environment Software - Manual (Page 24)

time used by threads that simulate the virtual processors. However, there are also threads
that simulate the I/O cards and disks in the virtual system. Capacity Advisor collects data
on all of these threads, which can cause the Capacity Advisor data for a specific virtual
machine’s CPU utilization to be greater than the number of virtual CPU cores (vCPUs)
associated with the virtual machine. Under certain load conditions, this can result in CPU
utilization of more than 100% being reported for a virtual machine.
• Capacity Advisor data for VM host CPU utilization can be lower than what the guest
operating system reports, especially during periods of high utilization. Capacity Advisor
records physical CPU utilization, which is the utilization of the actual cores on the VM host;
that is, the total utilization reported by Capacity Advisor is based on the CPU time that the
VM host allotted to each virtual machine. In contrast, the guest OS records virtual CPU
utilization, which includes time when the VM wants to run, but is suspended while another
VM is using the resources on the VM host.
Because Capacity Advisor corrects for these effects, the collected data has much less “noise” in
it, and better reflects the CPU time that was actually used by any one VM.
Data normalization
Capacity Advisor makes certain assumptions in its data analysis. These assumptions include
automatically adjusting for CPU platform differences based on a performance index. (The
performance index is constructed by normalizing collected data to selected benchmarks for the
source and destination systems, and in combination with clock speed in special cases).
If desired, you can add your own benchmark values to the database for use in calculating the
performance index for workload moves among systems with the same or different architectures.
(See capcustombenchmark in the
Appendix B (page 129) for more information.
Memory, network IO, and disk IO usage are not normalized.
NOTE:
Using benchmarks for data normalization is new with the 6.0 release. This change affects
workloads defined with static profiles in previous releases because they use clock speed to
determine performance. Such workloads that are still used for planning should be redefined or
edited in Capacity Advisor 6.0 to improve the accuracy of the performance measure.
Resources for which Capacity Advisor collects data
HP Insight Capacity Advisor software collects and analyzes data for utilization of the following
resources:
•
CPU cores
• Memory
• Network I/O
• Disk I/O
• Power
Upper bounds
Upper bounds represent the maximum capacity of a resource for a given system. The maximum
capacity is used in Capacity Advisor for items such as the network and disk I/O utilization graphs
of systems, the graphs and values shown in a profile viewer, and the Capacity Advisor Smart
Solver calculations.
CPU capacity The maximum CPU capacity of a system is the product of the number of CPU
cores and the clock speed of the system.
Memory The maximum capacity of memory is the amount of memory on the system.
24 Key Capacity Advisor concepts