How to Perform VMware Hot Add [2 Step-by-Step Methods]

What is VMware Hot Add

VMware Hot Add enables you to add hardware resources to running virtual machines (VMs) without powering them down. It allows administrators to dynamically scale resources such as CPU and memory without interrupting VM operations, which is important in environments that require high availability and minimal downtime.

VMware Hot Add eliminates the downtime of adding or upgrading resources such as CPU and memory that require the virtual machine to be powered off, enabling administrators to add:

👉VMware Hot Add CPU: Increases the number of vCPUs allocated to a virtual machine.
👉VMware Hot Add Memory: Adds more memory to a running virtual machine.

How to Perform VMware Hot Add

The following are two methods to perform a VMware Hot Add on CPU and memory in a VMware environment.

Perform Hot Add in vCenter

Prerequisite

Before performing a VMware Hot Add, ensure that the following prerequisites are met:

1. VMware vSphere and ESXi versions: vSphere and ESXi must be version 5.0 or later.
2. Virtual machine hardware version: The version should be 7 or higher.
3. VMware Tools: It must be installed and running on the virtual machine’s guest operating system.
4. Guest OS Compatibility: The guest OS must support CPU or memory hot add.
5. vCenter and ESXi Configuration: Hot add must be enabled for ESXi hosts and configured in vCenter.
6. Sufficient resources: The ESXi host should have sufficient resources (CPU and memory) allocated to the virtual machines.

Step 1. Enable Hot Add on the Virtual Machine

Before hot add CPU or memory to a running virtual machine, you must enable the feature in the virtual machine’s settings. Here’s how to enable the CPU and memory hot-add feature.

▶Log in to the VMware vSphere Client or vCenter:

Open the vSphere Client (or vCenter) and log in with administrator credentials.

▶Select the virtual machine:

In the vSphere inventory, select the virtual machine you want to modify.

▶Edit virtual machine settings:

Right-click the virtual machine and select Edit Settings.

▶Enable CPU and memory hot-add:

In the VM Options tab, expand the Advanced section.

Check the Enable CPU Hot Add and Enable Memory Hot Plug checkboxes.

Click OK to save the changes.

📌Note: These options must be enabled before adding CPU or memory. Hot Add cannot be enabled while the virtual machine is running, so you must configure these settings when you power off the virtual machine. When Hot Add is enabled, you can continue adding resources to the virtual machine while running.

Step 2. Add CPU or Memory to a Running Virtual Machine

Once hot add is enabled, you can add CPU or memory to a virtual machine without shutting it down.

◆Access the virtual machine settings:

Right-click on the virtual machine and select Edit Settings again.

◆Add CPU or Memory:

Add the CPU: Click the CPU section under the Virtual Hardware tab.

Add as many virtual CPUs (vCPUs) as needed.

Add memory: Under the Virtual Hardware tab, click the Memory section.

Increase the size of the memory (RAM) as needed.

◆Apply changes:

After selecting the number of CPUs or memory size, click OK to apply the changes.

The virtual machine does not need to be restarted and the operating system will detect the new resource.

Perform VMware Hot Add in PowerCLI

You can utilize PowerCLI cmdlets to enable the Hot Add feature and add resources to a running virtual machine to perform a VMware Hot Add of CPU and memory resources.

Step 1. Connect to vCenter Server

First, you need to connect to your vCenter server using PowerCLI.

Step 2. Enable Hot Add on the VM

If hot add is not already enabled on the VM, you need to enable it first.

👉1. Enable CPU Hot Add and Memory Hot Add on the virtual machine:

👉2. Verify Hot Add is Enabled:

Step 3. Add CPU or Memory to a Running Virtual Machine

When hot add is enabled, you can perform a hot add operation to add CPU or memory to a running virtual machine.

🔶1. Add CPUs to a running virtual machine:

To add more CPUs to a running virtual machine, use the following command:

🔶2. Add Memory to a Running VM:

To add more memory to the running VM, use the following command:

Efficient VMware Backup Tool to Protect Data

Before implementing VMware Hot Add, first, make sure that the virtual machine is functioning properly and that no important data, etc. in it has been lost. Here, recommend you to protect your virtual environment with AOMEI Cyber Backup, a professional backup software that provides you with powerful and user-friendly backup options for VMware.

Centralized Management: You can backup virtual machines from a central console without installing agents on each VM.
Fast Disaster Recovery: You can instant restore entire VMware virtual machines to a usable state without having to recreate and reconfigure new VMs, reducing downtime and potential financial loss.
Backup to all Locations: You can save your VM backup to local storage, external storage, NAS drive/network share, and support backup VMware to Amazon S3 storage.
Different Backup Methods: It supports full, differential, and incremental backup types, enabling you to back up virtual machines in both running and off states.

Simple steps to backup and restore in VMware

Step 1. Log into the AOMEI Cyber Backup Console, navigate to Source Device > VMware > + Add VMware Device to Add vCenter or Standalone ESXi. Then enter Device Information and User Information and click Confirm.

Step 2. Navigate to Backup Task > Create New Task, and select VMware ESXi Backup as the Device Type. Then configure the Task Name, Device, Target, Schedule, and Archive.

• Device: Cover multiple VMs on the host within one backup task.
• Target: You can choose to back up to a local path, or a network path.
• Schedule: You can perform full, differential, or incremental backup, and automate execution according to the frequency you can specify.

• Archive: You can add an Amazon S3 bucket, and archive backup versions to it.

Step 3. Click Start Backup, select Add the schedule, and start backup now, or Add the schedule only.

Step 4. After creating the backup task, you can check the task in the Backup Task tab. When you need to restore the backup, click…> Restore.

Conclusion

The VMware Hot Add is a powerful feature that enhances the flexibility and scalability of virtualized environments. Helping to maintain service continuity, reduce downtime, and simplify management, administrators can effectively utilize VMware Hot Add to enhance their VMware infrastructure and provide more efficient and responsive services to users.