ESX reporting memory Swap in and swap out rate

Products

• VMware vSphere ESXi
• VMware vSphere ESXi 7.0
• VMware vSphere ESXi 8.0

Issue/Introduction

• ESX hosts showing swap in rate and swap out rate constantly in the performance tab:
  
  
  
  
• When clicking on an ESX host in vCenter, memory utilization is low.
  
  
• Any third party monitoring tool generating alarm for memory swap.
  
  
• From the logs, ballooning is not found for these VMs, even though in VMtools, balloon driver is enabled.

Cause

Configuring memory limit or reservations for virtual machines can result increase swap in\out rate.

Resolution

esxtop commands for memory show swap current count.

• Check swcur parameter and  swap /MB and Curr values:
  
  
  
  
• The above example for esxtop swapcur suggests swap is happening on 2 VMs

Check settings of VM, we have Memory limit configured:

 

• This setting defines the maximum amount of memory that the VM can use. Even if the VM is configured with a larger amount of memory, the limit restricts the VM to a maximum of this value.
  
  
• Change this limit to Unlimited and reload VMX using Reloading a vmx file without removing the virtual machine from inventory

Additional Information

For more troubleshooting, refer:

vSphere Monitoring and Performance