What is Hotplug in VMware?
Hotplug in VMware refers to the ability to add or remove virtual hardware (such as CPUs, memory, and network adapters) while the VM is running, without requiring a reboot.
Why is Hotplug Used?
Hotplug is useful for:
✅ Minimizing downtime – No need to restart the VM when adding resources.
✅ Dynamic resource scaling – Useful in environments where workloads fluctuate.
✅ Optimizing performance – Helps scale VMs on demand in cloud and enterprise environments.
✅ Testing and development – Quickly modify VM configurations without disruptions.
How to Enable Hotplug in VMware?
1️⃣ Enable CPU Hotplug
- Power Off the VM.
- Go to VM Settings → Options → Advanced → Edit Configuration.
- Add or modify the following parameter:
cpuid.coresPerSocket = "1"
- Check the "Enable CPU Hotplug" option under VM Options → Advanced.
2️⃣ Enable Memory Hotplug
- Power Off the VM.
- Go to VM Settings → VM Options → Memory Hot Add.
- Enable "Hot Add Memory".
3️⃣ Enable Network Adapter Hotplug
- Power On the VM.
- Open VMware vSphere Client → Select the VM.
- Click Edit Settings → Add New Network Adapter → Connect.
4️⃣ Enable Disk Hotplug
- Power On the VM.
- In vSphere Client, navigate to the VM.
- Click Edit Settings → Add New Hard Disk → Apply.
How to Use Hotplug?
Once enabled, you can dynamically add or remove resources:
- CPU & Memory: Use VMware vSphere Client → Edit Settings to allocate additional CPUs or RAM.
- Disks & Network Adapters: Add or remove devices from VMware vSphere or ESXi without rebooting.
Limitations & Considerations
⚠️ Some guest OS (e.g., Windows Server 2012 and older Linux distros) may not support CPU/memory hotplug.
⚠️ Hot-remove for CPU is not supported (only hot-add).
⚠️ Memory hotplug works best with NUMA-aware applications.
