Hot Plug Option in VMware vSphere

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Today we will see the most important topic about the hotplug option in VMware vSphere.

There are two types of hot plugs available.

  • Enable Memory Hot Add
  • Enable CPU Hot Add

Enable Memory Hot Add

Memory hot add lets you add memory resources for a virtual machine while that virtual machine is powered on.

Enabling the memory hot add produces some memory overhead on the ESXi host for the virtual machine.

Prerequisites

  • Power off the virtual machine.
  • Verify that the virtual machine has a guest operating system that supports memory hot add functionality.
  • Verify that the virtual machine compatibility is ESXi 4.x and later.
  • Verify that VMware Tools is installed.

Procedure

vmware hot remove memory
vmware hot remove memory
  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, expand Memory, and select Enable to enable adding memory to the virtual machine while it is powered on.
vmware hot remove memory 2
vmware hot remove memory
  • Click OK.

You can now add memory to a virtual machine, even if the virtual machine is turned on.

Enable CPU Hot Add

Similarly, as Memory, you can enable CPU hot-add feature to the virtual machine. The CPU hot add option lets you add CPU resources to a running virtual machine which is disabled by default.

Prerequisites

Verify that the virtual machine is configured as follows.

  • Latest version of VMware Tools installed.
  • Guest operating system that supports CPU hot add.
  • Virtual machine compatibility is ESX/ESXi 4.x or later.
  • Virtual machine is powered off.
  • Required privileges: Virtual Machine.Configuration.Settings

Procedure

enable cpu hot plug vmware
enable cpu hot plug vmware
  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, expand CPU, and select Enable CPU Hot Add.
enable cpu hot plug vmware
enable cpu hot plug vmware
  • Click OK.

You can now add CPUs even if the virtual machine is powered on.

How to disable the Memory and CPU hot-add feature?

You can also disable this hotplug feature in the following ways if not willing to utilize it.

vSphere Client

  • Connect to the ESXi/ESX host or vCenter Server using the vSphere Client.
  • Power off the virtual machine.
  • Right-click the virtual machine and click Edit Settings.
  • Click the Options tab.
  • Click General > Configuration Parameters > Add Row.
  • Insert a new row with the name devices.hotplug and a value of false.
  • Power on the virtual machine.

HTML5 Client

  • From a web browser, connect to the HTML5 Client.
  • Log in with Administrator credentials.
  • Navigate to the virtual machine you want to modify.
  • Power off the virtual machine.
  • Right-click the virtual machine and select Edit Settings.
  • Click the VM Options tab.
  • Click Advanced > Edit Configuration.
  • Click Add Configuration Params to enter a new row
  • In the new row, enter the name devices.hotplug and a value of false.
  • Power on the virtual machine.

By editing the .vmx file

  • Power off the virtual machine.
    Access the ESXi/ESX service console using an SSH client.
  • Open the virtual machine configuration file (.vmx) in a text editor. The default location is: /vmfs/volumes/datastore_name/vm_name/vm_name.vmx
  • Add the line: devices.hotplug = “false”
  • Save and close the file.
  • Power on the virtual machine.

That’s all about hot add Hot Plug Option in VMware.

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