Upgrading VMware Virtual Infrastructure Setups

12 min read

In this article by Kunal Kumar and Christian Stankowic, authors of the book VMware vSphere Essentials, you will learn how to correctly upgrade VMware virtual infrastructure setups.

(For more resources related to this topic, see here.)

This article will cover the following topics:

  • Prerequisites and preparations
  • Upgrading vCenter Server
  • Upgrading ESXi hosts
  • Additional steps after upgrading

An example scenario

Let’s start with a realistic scenario that is often found in data centers these days. I assume that your virtual infrastructure consists of components such as:

  • Multiple VMware ESXi hosts
  • Shared storage (NFS or Fibre-channel)
  • VMware vCenter Server and vSphere Update Manager

In this example, a cluster consisting of two ESXi hosts (esxi1 and esxi2) is running VMware ESXi 5.5. On a virtual machine (vc1), a Microsoft Windows Server system is running vCenter Server and vSphere Update Manager (vUM) 5.5. This article is written as a step-by-step guide to upgrade these particular vSphere components to the most recent version, which is 6.0.

VMware vSphere Essentials

Example scenario consisting of two ESXi hosts with shared storage and vCenter Server

Prerequisites and preparations

Before we start the upgrade, we need to fulfill the following prerequisites:

  • Ensure ESXi version support by the hardware vendor
  • Gurarantee ESXi version support on used hardware by VMware
  • Create a backup of the ESXi images and vCenter Server

First of all, we need to refer to our hardware vendor’s support matrix to ensure that our physical hosts running VMware ESXi are supported in the new release. Hardware vendors evaluate their systems before approving upgrades to customers.

As an example, Dell offers a comprehensive list for their PowerEdge servers at http://topics-cdn.dell.com/pdf/vmware-esxi-6.x_Reference%20Guide2_en-us.pdf.

Here are some additional links for alternative hardware vendors:

When using Fibre-channel-based storage systems, you might also need to ensure fulfilling that vendor’s support matrix. Please check out your vendor’s website or contact support for this information.

VMware also offers a comprehensive list of tested hardware setups at http://www.vmware.com/resources/compatibility/pdf/vi_systems_guide.pdf. In their Compatibility Guide portal, VMware enabled customers to browse for particular server systems—this information might be more recent than the aforementioned PDF file.

Creating a backup of ESXi

Before upgrading our ESXi hosts, we also need to make sure that we have a valid backup. In case things go wrong, we might need this backup to restore the previous ESXi version. For creating a backup of the hard disk ESXi is installed on, there are a plenty of tools in the market that implement image-based backups. One possible solution, which is free, is Clonezilla. Clonezilla is a Linux-based live medium that can easily create backup images of hard disks.

To create a backup using Clonezilla, proceed with the following steps:

  1. Download the Clonezilla ISO image from their website. Make sure you select the AMD64 architecture and the ISO file format.
  2. Enable maintenance mode for the particular ESXi host. Make sure you migrate virtual machines to alternative nodes or power them off.
  3. Connect the ISO file to the ESXi host and boot from CD. Also, connect a USB drive to the host. This drive will be used to store the backup.
  4. Boot from CD and select Clonezilla live. Wait until the boot process completes.
  5. When prompted, select your keyboard layout (for example, en_US.utf8) and select Don’t touch keymap.
  6. In the Start Clonezilla menu, select Start_Clonezilla and device-image. This mode creates an image of the medium ESXi is running on and stores it in the USB storage.
  7. Select local_dev and choose the USB storage connected to the host from the list in the next step.
  8. Select a folder for storing the backup (optional).
  9. Select Beginner and savedisk to store the entire disk ESXi resides on as an image.
  10. Enter a name for the backup.
  11. Select the hard disk containing the ESXi installation and proceed. You can also specify whether Clonezilla should check the image after creating it (highly recommended). Afterwards, confirm the backup process. The backup job will start immediately.
  12. Once the backup completes, select reboot from the menu to reboot the host.

VMware vSphere Essentials

A running backup job in Clonezilla

To restore a backup using Clonezilla, perform the following steps after booting the Clonezilla media:

  1. Complete steps 1 to 8 from the previous guide.
  2. Select Beginner and restoredisk to restore the entire disk.
  3. Select the image from the USB storage and the hard drive the image should be restored on.
  4. Acknowledge the restore process.
  5. Once the restoration completes, select reboot from the menu to reboot the host.

For the system running vCenter Server, we can easily create a VM snapshot, or also use Clonezilla if a physical machine is used instead.

The upgrade path

It is very important to execute the particular upgrade tasks in the following order:

  1. Upgrade VMware vCenter Server
  2. Upgrade the particular ESXi hosts
  3. Reformat or upgrade the VMFS data stores (if applicable)
  4. Upgrading additional components, such as distributed virtual switches, or additional appliances

The first step is to upgrade vCenter Server. This is necessary to ensure that we are able to manage our ESXi hosts after upgrading them. Newer vCenter Server versions are downward compatible with numerous ESXi versions. To double-check this, we can look up the particular version support by browsing VMware’s Product Interoperability Matrix on their website. Click on Solution Interoperability, choose VMware vCenter Server from the drop-down menu, and select the version you want to upgrade to. In our example, we will choose the most recent release, 6.0, and select VMware ESX/ESXi from the Add Platform/Solution drop-down menu.

VMware vSphere Essentials

VMware Product Interoperability Matrix for vCenter Server and ESXi

vCenter Server 6.0 supports management of VMware ESXi 5.0 and higher. We need to ensure the same support agreement for any other used products, such as these:

  • VMware vSphere Update Manager
  • VMware vCenter Operations (if applicable)
  • VMware vSphere Data Protection

In other words, we need to upgrade all additional vSphere and vCenter Server components to ensure full functionality.

Upgrading vCenter Server

Upgrading vCenter Server is the most crucial step, as this is our central management platform. The upgrade process varies according to the chosen architecture. Upgrading Windows-based vCenter Server installations is quite easy, as the installation supports in-place upgrades. When using the vCenter Server Appliance (vCSA), there is no in-place upgrade; it is necessary to deploy a new vCSA and import the settings from the old installation. This process varies between the particular vCSA versions. For upgrading from vCSA 5.0 or 5.1 to 5.5, VMware offers a comprehensive article at http://kb.vmware.com/kb/2058441.

To upgrade vCenter Server 5.x on Windows to 6.0 using the Easy Install method, proceed with the following steps:

  1. Mount the vCenter Server 6.x installation media (VMware-VIMSetup-all-6.0.0-xxx.iso) on the server running vCenter Server. Wait until the installation wizard starts; if it doesn’t start, double-click on the CD/DVD icon in Windows Explorer.
  2. Select vCenter Server for Windows and click on Install to start the installation utility.
  3. Accept the End-User License Agreement (EULA).
  4. Enter the current vCenter Single-Sign-On password and proceed with the next step.
  5. The installation utility begins to execute pre-upgrade checks; this might take some time. If you’re running vCenter Server along with Microsoft SQL Server Express Edition, the database will be migrated to VMware vPostgres.
  6. Review and change (if necessary) the network ports of your vCenter Server installation.
  7. If needed, change the directories for vCenter Server and the Embedded Platform Controller (ESC).
  8. Carefully review the upgrade information displayed in the wizard. Also verify that you have created a backup of your system and the database. Then click on Upgrade to start the upgrade.

After the upgrade, vSphere Web Client can be used to connect to the upgraded vCenter Server system. Also note that the Microsoft SQL Server Express Edition database is not used anymore.

Upgrading ESXi hosts

Upgrading ESXi hosts can be done using two methods:

  • Using the installation media from the VMware website
  • vSphere Update Manager

If you need to upgrade a large number of ESXi hosts, I recommend that you use vSphere Update Manager to save time, as it can automate the particular steps. For smaller landscapes, using the installation media is easier. For using vUM to upgrade ESXi hosts, VMware offers a guide on their knowledge base at http://kb.vmware.com/kb/1019545.

In order to upgrade an ESXi host using the installation media, perform the following steps:

  1. First of all, enable maintenance mode for the particular ESXi host. Make sure you migrate the virtual machines to alternative nodes or power them off.
  2. Connect the installation media to the ESXi host and boot from CD.
  3. Once the setup utility becomes available, press Enter to start the installation wizard.
  4. Accept the End-User License Agreement (EULA) by pressing F11.
  5. Select the disk containing the current ESXi installation. In the ESXi found dialog, select Upgrade.
  6. Review the installation information and press F11 to start the upgrade.
  7. After the installation completes, press Enter to reboot the system.

After the system has rebooted, it will automatically reconnect to vCenter Server. Select the particular ESXi host to see whether the version has changed. In this example, the ESXi host has been successfully upgraded to version 6.0:

VMware vSphere Essentials

Version information of an updated ESXi host running release 6.0

Repeat all of these steps for all the remaining ESXi hosts. Note that running an ESXi cluster with mixed versions should only be a temporary solution. It is not recommended to mix various ESXi releases in production usage, as the various features of ESXi might not perform as expected in mixed clusters.

Additional steps

After upgrading vCenter Server and our ESXi hosts, there are additional steps that can be done:

  • Reformating or upgrading VMFS data stores
  • Upgrading distributed virtual switches
  • Upgrading virtual machine’s hardware versions

Upgrading VMFS data stores

VMware’s VMFS (Virtual Machine Filesystem) is the most used filesystem for shared storage. It can be used along with local storage, iSCSI, or Fibre-channel storage.

Particularly, ESX(i) releases support various versions of VMFS. Let’s take a look at the major differences:








Supported by

ESX 2.x, ESXi 3.x/4.x (read-only)

ESX(i) 3.x and higher

ESXi 5.x and higher

Block size(s)

1, 8, 64, or 256 MB

1, 2, 4, or 8 MB

1 MB (fixed)

Maximum file size

1 MB block size: 456 MB

8 MB block size: 2.5 TB

64 MB block size: 28.5 TB

256 MB block size: 64 TB

1 MB block size: 256 MB

2 MB block size: 512 GB

4 MB block size: 1 TB

8 MB block size: 2 TB

62 TB

Files per volume

Ca. 256 (no directories supported)

Ca. 37,720

Ca. 130,690

When migrating from an ESXi version such as 4.x or older, it is possible to upgrade VMFS data stores to version 5. VMFS 2 cannot be upgraded to VMFS 5; it first needs to be upgraded to VMFS 3. To enable the upgrade, a VMFS 2 volume must not have a block size more than 8 MB, as VMFS 3 only supports block sizes up to 8 MB. In comparison with older VMFS versions, VMFS 5 supports larger file sizes and more files per volume. I highly recommend that you reformat VMFS data stores instead of upgrading them, as the upgrade does not change the filesystem’s block size. Because of this limitation, you won’t benefit from all the new VMFS 5 features after an upgrade.

To upgrade a VMFS 3 volume to VMFS 5, perform these steps:

  1. Log in to vSphere Web Client.
  2. Go to the Storage pane.
  3. Click on the data store to upgrade and go to Settings under the Manage tab.
  4. Click on Upgrade to VMFS5.
  5. Then click on OK to start the upgrade.

VMware vNetwork Distributed Switch

When using vNetwork Distributed Switches (also often called dvSwitches) it is recommended to perform an upgrade to the latest version. In comparison with vNetwork Standard Switches (also called vSwitches), dvSwitches are created at the vCenter Server level and replicated to all subscribed ESXi hosts. When creating a dvSwitch, the administrator can choose between various dvSwitch versions. After upgrading vCenter Server and the ESXi hosts, additional features can be unlocked by upgrading the dvSwitch. Let’s take a look at some commonly used dvSwitch versions:


vDS 5.0


vDS 5.1


vDS 5.5


vDS 6.0


Compatible with

ESXi 5.0 and higher

ESXi 5.1 and higher

ESXi 5.5 and higher

ESXi 6.0

Common features

Network I/O Control, load-based teaming, traffic shaping, VM port blocking, PVLANs (private VLANs), network vMotion, and port policies

Additional features

Network resource pools, NetFlow, and port mirroring

VDS 5.0 +, management network rollback, network health checks, enhanced port mirroring, and LACP (Link Aggregation Control Protocol)

VDS 5.1 +, traffic filtering, and enhanced LACP functionality

VDS 5.5 +, multicast snooping, and Network I/O Control version 3 (bandwidth guarantee)

It is also possible to use the old version furthermore, as vCenter Server is downward compatible with numerous dvSwitch versions. Upgrading a dvSwitch is a task that cannot be undone. During the upgrade, it is possible that virtual machines will lose their network connectivity for some seconds. After the upgrade, older ESXi hosts will not be able to participate in the distributed switch setup.

To upgrade a dvSwitch, perform the following steps:

  1. Log in to vSphere Web Client.
  2. Go to the Networking pane and select the dvSwitch to upgrade.
  3. Lorem…..

After upgrading the dvSwitch, you will notice that the version has changed:

VMware vSphere Essentials

Version information of a dvSwitch running VDS 6.0

Virtual machine hardware version

Every virtual machine is created with a virtual machine hardware version specified (also called VMHW or vHW). A vHW version defines a set of particular limitations and features, such as controller types or network cards. To benefit from the new virtual machine features, it is sufficient to upgrade vHW versions. ESXi hosts support a range of vHW versions, but it is always advisable to use the most recent vHW version. Once a vHW version is upgraded, particular virtual machines cannot be started on older ESXi versions that don’t support the vHW version. Let’s take a deeper look at some popular vHW versions:


vSphere 4.1


vSphere 5.1


vSphere 5.5


vSphere 6.0


Maximum vHW





Virtual CPUs




Virtual RAM

255 GB

1 TB

4 TB

vDisk size

2 TB

62 TB

SCSI adapters / targets


SATA adapters / targets

Not supported


Parallel / Serial Ports



USB controllers / devices per VM

1/20 (USB 1.x + 2.x)

1/20 (USB 1.x, 2.x + 3.x)

The upgrade cannot be undone. Also, it might be necessary to update VMware Tools and the drivers of the operating system running in the virtual machine.


In this article we learnt how to correctly upgrade VMware virtual infrastructure setups.

If you want to know more about VMware vSphere and virtual infrastructure setups, go ahead and get your copy of Packt Publishing’s book VMware vSphere Essentials.

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Further resources on this subject:


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