Understanding esxtop Memory parameters

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides information about esxtop and memory statistics that can be used when troubleshooting performance issues

Environment

It is important to note that some statistics refer to guest physical memory while others refer to machine memory. "Guest physical memory" is the virtual-hardware physical memory presented to the VM. "Machine memory" is actual physical RAM in the ESX host.

Resolution

Esxtop shows the groups that use memory managed by VMKernel memory scheduler. These groups can be used for VMs or purely for user worlds running directly on VMKernel. You may see many pure user world groups on ESXi.

use 'V' command to show only the VM groups.

• "MEMSZ" (MB):
  For a VM, it is the amount of configured guest physical memory.
  
  
• "GRANT" (MB):
  For a VM, it is the amount of guest physical memory granted to the group, i.e., mapped to machine memory. The overhead memory, "OVHD" is not included in GRANT. The shared memory, "SHRD", is part of "GRANT".

• "SZTGT" (MB):

  The amount of machine memory to be allocated. (TGT is short for "target".) Note that "SZTGT" includes the overhead memory for a VM.

• "TCHD" (MB):

  The amount of guest physical memory recently used by the VM, which is estimated by VMKernel statical sampling.

• "%ACTV"

  Percentage of active guest physical memory, current value.

• "%ACTVS"

  Percentage of active guest physical memory, slow moving average. 

• "%ACTVF"

  Percentage of active guest physical memory, fast moving average.

• "%ACTVN"

  Percentage of active guest physical memory in the near future.

• "MCTL?"

  Memory balloon driver is installed or not.

• "MCTLSZ" (MB)

  The amount of guest physical memory reclaimed by balloon driver.

• "MCTLTGT" (MB)

  The amount of guest physical memory to be kept in balloon driver. (TGT is short for "target".)

• "MCTLMAX" (MB)

  The maximum amount of guest physical memory reclaimable by balloon driver.

• "SWCUR" (MB)

  Current swap usage.

• "SWR/s" (MB)

  Rate at which memory is being swapped in from disk. Note that this stats refers to the VMKernel swapping not the guest swapping.

• "SWW/s" (MB)

  Rate at which memory is being swapped out to disk. Note that this stats refers to the VMKernel swapping not the guest swapping.

• "SHRD" (MB)

  Amount of guest physical memory that are shared.

• "ZERO" (MB)

  Amount of guest physical zero memory that are shared. This is an internal counter.

• "SHRDSVD" (MB)

  Estimated amount of machine memory that are saved due to page sharing.

• "COWH" (MB)

  Amount of guest physical hint pages for page sharing. This is an internal counter.

• "OVHDUW" (MB)

  Amount of overhead memory reserved for the vmx user world of a VM group. This is an internal counter.

• "OVHD" (MB)

  Amount of overhead memory currently consumed by a VM.

• "OVHDMAX" (MB)

  Amount of reserved overhead memory for the entire VM