HP Capacity Advisor 7.2 User Guide

Many IT organizations use the power of two for the number of cores in their virtual machines. This
means they have VMs with one, two, four, or eight cores. Because the overhead for having a few
extra cores in a VM is small, it is reasonable to standardize the number of cores per VM to the
power of two. In terms of savings on the VM host, taking the time to decide if seven cores will
suffice instead of eight cores is generally not worth the effort.
However, software licenses can make the cost of one extra core very expensive. Some software
packages cost over $20,000 per core. In that case, the difference between five cores and eight
cores is a lot of money.
As a cost-conscious administrator, you think it would be valuable to create an HP SIM collection
of servers with per-core software licensing costs. Or, alternatively, create a separate collection for
each core-licensed software package. That way, you could run a query against the collection every
few weeks to discover any cores that could be removed from the VMs and save on licensing costs.
For example, if you get a request to deploy a new database instance, the query could be run
against a database collection. It would identify VMs that could cede a vCPU, freeing enough
licenses for the new instance.
Requirements
This example assumes you have ESX, Hyper-V, and HP VMs in the data center.
The example also assumes that the target CPU utilization should never go above 80% for more
than 15 minutes at a time.
To be able to look for VMs with one too many cores, the query could cover the following situations:
• The VM has two cores and the 15-minute sustained CPU load is less than 1/2 of 80%.
• The VM has three cores and the 15-minute sustained CPU load is less than 2/3 of 80%.
• The VM has four cores and the 15-minute sustained CPU load is less than 3/4 of 80%.
Depending on licensing costs and workload volatility, further stages could be added to the query.
NOTE: This query only looks for systems that are VMs, because physical systems generally cannot
change the number of cores that are allocated to them. But a similar query for physical systems
could be written if licensing costs justify it. For example, a query could locate physical systems
with eight cores that might be better run in a five core VM.
Defining the query
Defining this analysis query consists of three basic steps:
1. Creating and naming the new query.
2. Selecting the data to include in the query results.
3. Defining the filter that selects which systems appear in the query results.
Creating and naming the query
1. In the Analysis tab, select Actions→New....
126 Using Capacity Analysis