HP Capacity Advisor 7.2 User Guide

Compare power use between NewVMhost1 running four VMs (including m-teal2) and m-teal2
running on an older physical server.
Comparing energy use and costs across all servers included in a power consolidation scenario
can provide a realistic estimation of savings achievable by moving work to servers with newer
power saving technology.
TIP: Though not discussed here, this planning task also demonstrated potential efficiencies in
CPU and memory use. Should you try this on your own, review the resulting reports for improvements
in CPU and memory utilization as well as power usage.
Data modeling in the Scenario Editor
The Scenario Editor can model standalone systems and VMs. Standalone systems have a dedicated
number of CPU cores, a dedicated amount of memory, dedicated HBA (Host Bus Adapter) cards,
and dedicated NICs (Network Interface Cards). VMs on a VM host share the host’s CPU cores,
have their own dedicated memory, and the share the host’s HBAs and NICs.
Different hypervisors manage memory differently. HPVM has dedicated memory for VMs (while
HPVM has a balloon driver that allows for memory to be shared, that driver is manually controlled,
so Capacity Advisor models it as dedicated memory). ESX and HyperV now offer options to take
memory from VMs that do not need it to make room for more VMs on the host. Just as ESX changed
from reserving all of the memory of a VM to reserving almost none, we have changed how Capacity
Advisor models the memory. Capacity Advisor now models the memory used by ESX VMs as a
shared resource.
For example, if an HPVM hypervisor hosts two VMs with 4 GB of RAM each, the Scenario Editor
models those two VMs as using 8 GB of RAM on their host. Those two VMs will always take 8 GB
from the host, even if the OS and applications inside the VMs are only using 1 GB in each
VM. However, when the Scenario Editor computes the memory use on an ESX host, the two 4 GB
VMs that use 1 GB each use a total of 2 GB of memory on the host.
154 Planning with Capacity Advisor