Guest operating system customization is supported only if a number of requirements are met.

The most current version of VMware Tools must be installed on the virtual machine or template to customize the guest operating system during cloning or deployment.

The guest operating system being customized must be installed on a disk attached as SCSI node 0:0 in the virtual machine configuration.

Virtual machines that reside on hosts running ESX Server 3.0.x or earlier have additional disk requirements:

On a Windows guest operating system, the active partition (the partition containing boot.ini) and the system partition (the partition containing the system directory, for example, \WINNT or WINDOWS) must be on the same virtual disk. The active partition and the system partition do not need to be the same partition.

On a Linux guest operating system, the virtual disk containing the system partition (the partition containing the /etc directory) must reside on the SCSI 0:0 node.

Customization of Windows guest operating systems requires the following conditions:

Microsoft Sysprep tools must be installed on the vCenter Server system. See Installing the Microsoft Sysprep Tools.

The ESX/ESXi host that the virtual machine is running on must be 3.5 or later.

Guest operating system customization is supported on multiple Windows operating systems. To verify customization support for Windows operating systems and compatible ESX/ESXi hosts, see VMware vSphere Compatibility Matrixes.

Customization of Linux guest operating systems requires the following conditions:

Perl must be installed in the Linux guest operating system.

The clone or template must have a root volume formatted with an ext2, ext3, or ReiserFS file system.

Guest operating system customization is supported on multiple Linux distributions. To verify customization support for Linux distributions and compatible ESX/ESXi hosts, see VMware vSphere Compatibility Matrixes.