Enabling Memory Hotplug for Virtual Machines

If a guest operating system supports the memory hotplug functionality, you can enable this functionality for the virtual machine. Once the memory hotplug functionality is turned on, you can configure the amount of memory available to your virtual machines even if they are running. Currently, the following systems come with the memory hotplug support:

Linux (both x86 and x64 versions)

• CentOS 5.3 and higher
• Red Hat Enterprise LInux 5.3 and higher
• Fedora 13 and higher
• SUSE Linux Enterprise Server 10 and higher
• Ubuntu 10.04 and higher

  Windows

• x64 version of Windows Server 2008 R2 (Datacenter Edition)
• x86 and x64 versions of Windows Server 2008 (Standard Edition)
• x86 and x64 versions of Windows Server 2008 (Enterprise Edition)
• x86 and x64 versions of Windows Server 2008 (Datacenter Edition)
• x86 and x64 versions of Windows Server 2003 (Enterprise Edition)

By default, memory hotplug support is disabled for all newly created virtual machines. To enable this functionality, you can use the --mem-hotplug option of the pctl set command. For example, to enable the memory hotplug support in the MyVM virtual machine that runs one of the supported operating systems, stop the MyVM virtual machine and run this command:

# pctl set MyVM --memory-hotplug on

set mem hotplug: 1

The VM has been successfully configured.

Once the functionality is enabled, you can configure the amount of memory for the MyVM virtual machine even it is running.

To disable the memory hotplug support in the MyVM virtual machine, use this command:

# pctl set MyVM --mem-hotplug off

set mem hotplug: 0

The VM has been successfully configured.

The changes will come into effect on the next virtual machine start.