Virtual Machine UUID Format

Products

• VMware vCenter Server

Issue/Introduction

This article describes the UUID system for virtual machines within vCenter Server.

Environment

VMware vCenter Server

Resolution

vCenter Server assigns a unique, 16-byte identifier string (a UUID) to each virtual machine it manages. The UUID is stored in the virtual machine's configuration file (.vmx file) and can be accessed within the vCenter Server UI client or SDK APIs. The value of the UUID is fixed; the format of the UUID differs, depending on the way in which it is retrieved.

In the virtual machine's configuration file, the UUID is stored under the "uuid.bios" key. The format separates the bytes with spaces and a hyphen. A sample UUID looks like this:

00 11 22 33 44 55 66 77-88 99 AA BB CC DD EE FF

However, the format of the UUID is different when it is used as a virtual machine identifier in the /vm path hierarchy. There the UUID is presented in a format described in ISO 11578. In this format, the UUID has a different byte order, and several hyphens are used to separate some of the bytes. The sample UUID shown above would be reported in this format for ISO 11578 compatibility:

33221100-5544-7766-8899-AABBCCDDEEFF