What about VMware Virtual Machine hardware versions

It depends on the features you need. If you want for example use the “Changed Blocked Tracking (CBT)” feature, you need at least hardware version 7.

In ESX 3.x hardware version 4 is introduced, in vSphere 4.x hardware version 7 is introduced and in vSphere 5 hardware version 8 is introduced. Here is an overview of the hardware version and the features they have:

Hardware versionFeaturesProducts
8- Up to 32 vCPUs per VM
- Maximum 1 TB RAM per VM
- 3-D graphics and high-definition audio
- Smart-card reader support
- USB 3.0 devices are supported
- Improved network driver for the E1000e
network adapter, provided by VMware tools
- Greater resources are available with vCloud Director 1.5
Hardware version 8 is the default for new VM in:
- ESX 5.x
- Fusion 4.x
- Workstation 8.x
- Player 4.x
7- Serial Attached SCSI (SAS) virtual device for Microsoft Cluster Service — Provides support for running Windows Server 2008 in a Microsoft Cluster Service configuration.
- IDE virtual device — Ideal for supporting older operating systems that lack SCSI drivers.
- VMXNET Generation 3. VMXNET is optimized for performance in a virtual machine 
- Virtual Machine Hot Plug Support— Provides support for adding and removing virtual devices, adding virtual CPUs, and adding memory to a virtual machine without having to power off the virtual machine.
- Change Block Tracking (CBT) support. Incease VADP backups
Hardware version 7 is the default for new VM in:
- ESX 4.x
- Fusion 3.x
- Fusion 2.x
- Workstation 7.x & 6.5
- Player 3.x
- Server 2.x
4Hardware version 4 is the default for new VM in:
- ESX 3.x
- ACE 2.x
- Fusion 1.x
- Player 2.x
3 Hardware version 3 is the default for new VM in:
- ESX 2.x
- GSX Server 3.x

Considerations before upgrading the hardware version of the VM:

  • Important to know is that upgrading the hardware version of the VM requires downtime!
  • Virtual machines with hardware version 7 can only run on ESX(i) 4.x and ESXi 5.x. Virtual machines with hardware version 8 can only run on ESXi 5.x
  • When you upgrade from virtual hardware version 4 to version 8, the upgrade is reversible if you take a virtual machine backup or snapshot before performing the upgrade.
  • To automate this process, consider using Update Manager for virtual machine upgrades
  • Update Manager takes automatic snapshots before performing virtual machine upgrades
  • Be sure to upgrade first the VMware tools of the VM.  I you upgrade the virtual hardware before you upgrade VMware Tools, the virtual machine might lose its network settings
  • Verify that all VMs and .VMDK files are stored on VMFS3, VMFS5 or NFS volumes

Steps in the hardware version upgrade process:

  • Do an inventory on the current hardware and VMware tools versions. This can be done for example by using the vCenter client, RVtools utility or PowerCLI

  • Install or upgrade the VMware tools (reboot required)

  • Power on the VM

  • Before upgrading create a backup or snapshot of the VM

  • Backup the NIC IP settings with the VMUpgradeHelper.exe command.

  • Power off the VM

  • Upgrade Virtual Hardware

  • Start VM  (reboot after the new hardware is discovered)

  • Check if all the IP addresses are correct

Downgrade methods:

There is no button in vCenter to revert back to an earlier Hardware version. Here are two methods to go back to an earlier version of the hardware version:

  • Create before upgrading the hardware version a snapshot when the VM is powered down.
  • Using VMware Converter

Upgrading issues to know about:

  • Upgrading virtual hardware in ESX 4.x may cause Windows 2008 disks to go offline (more information can be found here )
  • After a hardware version upgrade the configuration can be messed up on  for example Microsoft ISA, Microsoft NLB clusters and RSA servers
  • After upgrading a Windows virtual machine from hardware version 4 to hardware version 7, virtual NIC settings (such as static IP configuration) are lost. Make sure you backup the VM IP settings with the VMUpgradeHelper.exe command.
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