Verify Requirements

The first step in the upgrade process is ensuring that the hardware and software in your environment meet the vSphere 5 requirements. Reading what the requirements are and to begin to formulate a plan as to how you are going to upgrade your vSphere environment is a good place to start. The vSphere Upgrade Guide by VMware describes how to upgrade from previous versions of vSphere to the latest release of vSphere 5. This detailed guide provides an excellent source for the process of upgrading, and important requirements are detailed in this guide.

Upgrade Overview and Process

Upgrading to vSphere 5 must be done in a particular process. The order of the upgrade process has to be followed and completed before beginning the next phase. In The vSphere Upgrade Guide you will find many important options and requirements. The four phases of the upgrade are listed below and this paper is going to summarize these tasks.

Phase 1 Upgrade vCenter Server
Phase 2 Upgrade ESXi hosts
Phase 3 Upgrade Virtual Machine Hardware Version
Phase 4 Upgrade VMFS3 file system to VMFS5

Phase 1 Upgrade vCenter Server

When it is time to begin the first phase of the upgrade process, there are important things to note. You can upgrade vCenter Server to version 5, while still maintaining the hosts, virtual machines (VMs), and VMFS at earlier releases. However, the upgrade goes only in one direction, so if you need to revert back to the previous release, you will need to restore from a backup.

Whether the vCenter Server is on a physical machine or a virtual one, it still must meet certain requirements. The minimum hardware requirements are two Intel or AMD 64-bit CPUs running at 2.0GHz or faster, 4GB of RAM, and 4GB of disk space. The main software requirements are a 64-bit operating system, and a 64-bit DSN to connect to the database. In addition, there is a software requirement of Microsoft .NET 3.5 SP1 Framework.

If the vCenter Server 4.x is on a 64-bit machine, you can upgrade to vCenter Server 5.0 on the same machine. Downtime is required for the upgrade of the vCenter Server, but the hosts and VMs are not required to be down during the vCenter Server upgrade. During this down time, any feature of vSphere, such as Distributed Resource Scheduler (DRS), vMotion, Storage vMotion, or any other feature that requires the vCenter Server will not function. However, High Availability (HA) will still function during the upgrade process, because it does not require vCenter Server to function.

If you are upgrading the vCenter Server to a different machine, there are a number of issues that you need to be aware of, but start by backing up the vCenter Server database. In addition, you can use the Data Migration Tool that comes with the vCenter installation media. This tool can be used to back up the Lightweight Directory Access Protocol (LDAP) data, port settings, SSL certificates, and licenses. Depending on the existing environment, things to check are whether you are upgrading from a physical machine to a virtual machine, physical machine to physical machine or, virtual machine to virtual machine. Also, are you upgrading from a 32-bit system to a 64- bit system or, 64-bit system to 64-bit system?

You have an option to upgrade ESXi hosts by utilizing the VMware Update Manager (VUM), which also will need to be upgraded and running on a 64-bit machine. Update Manager 5.0 can be used to upgrade and patch ESXi hosts. One of the new features to VUM is the ability to remediate hosts in parallel, since before vSphere 5 you could only upgrade one host at a time. To upgrade Update Manager, use the vCenter Installer. In addition, VUM can be used to upgrade the virtual hardware and VMware tools of a virtual machine, and schedule the reboot of the virtual machine instead of rebooting immediately.

Upgrade the vSphere Client and install the Update Manager plug-in to finish the first phase of the upgrade process. This can be accomplished by using the vCenter Server Installer to upgrade the vSphere Client, and then the plug-in manager to upgrade the VUM plug-in.

Phase 2 upgrade ESXi

After upgrading vCenter Server, vSphere Update Manager, and the vSphere Client, the next phase is to upgrade the ESX/ESXi hosts to ESXi 5.0. The ESXi host upgrade does pose some challenges in meeting hardware requirements, new boot device options, and several different methods for upgrading the host; simply understanding the architecture of the ESXi host comes in handy.