VMware HotAdd (Hot Plug) and When to Enable It

That helps most where demand moves around. If a production application suddenly takes on more load, you can give it extra CPU cores or memory right away and keep its performance up. HotAdd buys you operational flexibility and keeps downtime out of the picture.

Enabling it does come with prerequisites. The virtual machine has to use a compatible hardware version, the guest operating system has to support hot-add, and VMware Tools should be installed and current. The setting also has to be turned on in the VM configuration before the machine is powered on.

Turn HotAdd on where flexibility and uptime matter, particularly for business-critical workloads that cannot be shut down. Not every VM needs it. An environment with stable, predictable workloads gains little from it. Frequent resource changes can also cause short performance swings, so plan them rather than making them on a whim.

Used in the right places, HotAdd makes resources easier to scale and keeps virtualized infrastructure running through the changes.

Q1: What resources can be added using HotAdd?

CPU cores, memory and some virtual disks, while the VM is running.

Q2: Does HotAdd eliminate downtime completely?

It saves you the shutdown when you expand resources, and you should still watch performance while the change happens.

Q3: Can HotAdd be enabled after the VM is powered on?

No, the setting has to be enabled while the VM is powered off.

Q4: Does every guest operating system support HotAdd?

No, the guest OS has to support CPU and memory hot-add.