| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Usage |
The percentage of physical CPU used by this component |
Percent |
A very high value for this measure indicates excessive CPU utilization by the component. The CPU utilization may be high because a few processes are consuming a lot of CPU, or because there are too many processes contending for a limited resource. If the ESX server being monitored is of version 3 or 3.5, then, an additional vim/console descriptor will appear for this test, which would report the CPU usage of the processes executing on the service console. A high value for the system/console descriptor indicates that one/more service console processes are consuming CPU resources excessively. The VMs descriptor on the other hand, reports the overall physical CPU usage of all VMs executing on the target vSphere/ESX server. In the event of high physical CPU usage by VMs, you can use the detailed diagnosis available for this descriptor to know which VMs are resource-intensive. |
| Memory_Overhead |
The total of all overhead metrics for powered-on virtual machines, plus the overhead of running vSphere services on this system resource. |
MB |
vSphere/ESXi virtual machines can incur two kinds of memory overhead:
- The additional time to access memory within a virtual machine.
- The extra space needed by the ESX/ESXi host for its own code and data structures, beyond the memory allocated to each virtual machine.
vSphere/ESXi memory virtualization adds little time overhead to memory accesses. Because the processor's paging hardware uses page tables (shadow page tables for software-based approach or nested page tables for hardware-assisted approach) directly, most memory accesses in the virtual machine can execute without address translation overhead.
The memory space overhead has two components:
- A fixed, system-wide overhead for the VMkernel
- Additional overhead for each virtual machine
Overhead memory includes space reserved for the virtual machine frame buffer and various virtualization
data structures, such as shadow page tables. Overhead memory depends on the number of virtual CPUs and
the configured memory for the guest operating system. vSphere/ESXi also provides optimizations such as memory sharing to reduce the amount of physical memory used on the underlying server. These optimizations can save more memory than is taken up by the overhead. |
| Swapped_memory |
The amount of memory that is swapped out of this system resource group which includes kernels, VMs and console. |
MB |
|
| Zero_memory |
The amount of memory that is zeroed out of this system resource. |
MB |
The "Memory Zero" amount will fluctuate as memory is over allocated. ESX will zero out the VM's memory to use with other VMs. The detailed diagnosis of this measure will reveal the "Memory Zero" amount for each VM. |
| Mapped_memory |
The amount of memory that is mapped by this system resource. |
MB |
|
| Memory_ShareSaved |
The amount of memory saved from the memory share that is allocated for this system resource. |
MB |
|
| Shared_memory |
The current amount of memory that is shared by this system resource. |
MB |
VMware ESX can share common memory pages across VMs. This includes pages from VMs running the same virtual machine OS and applications. |
| Touched_memory |
The amount of memory that has been touched i.e., read from or written to this system resource in the past X minutes, where X refers to the time period for which this test is executed. |
MB |
|