6.7

Table 1‑131. CPU Performance Enhancement Advice (Continued)
# Resolution
4 Turn off power management (also known as power-capping) in the BIOS. If power management is enabled, the secondary
host might enter lower performance, power-saving modes. Such modes can leave the secondary virtual machine with
insufficient CPU resources, potentially making it impossible for the secondary to complete all tasks completed on a primary in
a timely fashion.
5 Turn off hyperthreading in the BIOS. If hyperthreading is enabled and the secondary virtual machine is sharing a CPU with
another demanding virtual machine, the secondary virtual machine might run too slowly to complete all tasks completed on
the primary in a timely fashion.
Memory Active (MB)
The Memory Active chart displays active memory usage for fault tolerant virtual machines.
This chart is located in the Fault Tolerance view of the Virtual Machine Peformance tab. It is not
available at collection level 1.
Table 1‑132. Data Counters
Chart Label Description
Active Amount of guest physical memory in use by the fault tolerant virtual machine. Active memory is
estimated by VMkernel statistical sampling and represents the actual amount of memory the
virtual machine needs. Additional, unused memory may be swapped out or ballooned with no
performance impact.
n
Counter: active
n
Stats Type: Absolute
n
Unit: Megabytes (MB)
n
Rollup Type: Average (Minimum/Maximum)
n
Collection Level: 2 (4)
Make sure that the primary and secondary virtual machines have enough memory. If the
secondary system is not provisioned well, it might slow down performance of the primary virtual
machine or fail.
Chart Analysis
A virtual machine's memory size must be slightly larger than the average guest memory usage. This
enables the host to accommodate workload spikes without swapping memory among guests. Increasing
the virtual machine memory size results in more overhead memory usage.
If sufficient swap space is available, a high balloon value does not cause performance problems.
However, if the swapin and swapout values for the host are large, the host is probably lacking the amount
of memory required to meet the demand.
If a virtual machine has high ballooning or swapping, check the amount of free physical memory on the
host. A free memory value of 6% or less indicates that the host cannot meet the memory requirements.
This leads to memory reclamation, which might degrade performance. If the active memory size is the
same as the granted memory size, demand for memory is greater than the memory resources available. If
the active memory is consistently low, the memory size might be too large.
vSphere Monitoring and Performance
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