VMware released vSphere 6.7 Update 2 (U2) recently. Part of this release also introduced virtual hardware version 15 (vmx-15).

Vladan Seget

Vladan Seget is as an independent consultant, professional blogger, vExpert 2009-2018, VCAP-DCA/DCD, VCP, and MCSA. He has been working for over 20 years as a system engineer.

It's quite unusual to see the release of a new virtual hardware version with a version of vSphere that is not major but only an "Update 2." I think it's the first time in VMware's history.

Note that vmx-15 will only work on vSphere 6.7 U2 (and higher), so if you're running a lower version of vSphere, you won't be able to take advantage of the improvements present in this version. Even vSphere 6.7 GA or 6.7 U1 won't be able to power on virtual machines (VMs) configured with this virtual hardware version.

You must upgrade all hosts within your clusterto be able to run VMs configured with vmx-15. As a side note, VMs configured with vmx-15 won't run on VMware Cloud on Amazon Web Services (AWS). It's not compatible just yet.

What's new in VMware vmx-15 ^

We detailed the specs for virtual hardware 14 (vmx-14) a few months ago here: New in virtual machine hardware version 14. Compared to vmx-14, vmx-15 adds only a few new features.

Whereas only a minimal difference exists between vmx-14 and vmx-15, VMware made some other enhancements to vCenter Server 6.7 U2 worth looking at. In fact, the only difference between vmx-14 and vmx-15 is the fact that vmx-15 increases the ability to configure VMs with up to 256 virtual CPUs(vCPUs) compared to VMs with vmx-14 configurable for up to 128 vCPUs.

The table below gives an overview of support for different virtual hardware versions on different versions of vSphere.

Virtual hardware support by vCenter Server version

Virtual hardware support by vCenter Server version

However, the strange thing is that when creating new VMs using the vSphere Client in vSphere 6.7 U2, vmx-14 is still the default version by default. But we can change this default behavior, and later in the article we'll show you how.

Now let's focus on some other enhancements found in ESXi 6.7 U2 that might be of interest.

  • Standalone ESXCLI command package:ESXi 6.7 U2 provides a new standalone ESXCLI package for Linux separate from the vSphere Command-Line Interface (vSphere CLI) installation package. There's no update for the ESXCLI that's part of the vSphere CLI.
  • Precheck for upgrading vCenter Server systems: vCenter Server 6.7 U2 brings a new precheck when upgrading a vCenter Server system to ensure upgrade compatibility of the VMware vCenter Single Sign-On (SSO) service registration endpoints. This precheck shows you whether there is a possible mismatch with present machine vCenter SSO certificates before the start of an upgrade. It prevents upgrade interruptions that require manual workarounds and cause downtime.
  • Solarflare native driver:ESXi 6.7 U2 adds Solarflare native driver (sfvmk) support for Solarflare 10G and 40G network adapter devices (for example, the SFN8542 and SFN8522).
  • VMFS6 automatic unmap: There's support for VM File System 6 (VMFS6) automatic unmap processing on storage arrays and devices that report to ESXi hosts an unmap granularity value greater than 1 MB. On arrays that report granularity of 1 MB or less, there's support for the unmap if the granularity is a factor of 1 MB.
  • Support for VOMA: ESXi 6.7 U2 adds VMFS6 to the list of file systems that the vSphere On-disk Metadata Analyzer (VOMA) supports. This allows you to check and fix issues with VMFS volume metadata, Logical Volume Manager (LVM) metadata, and partition table inconsistencies. It is a command-line-based utility.

Where to check for the virtual hardware version ^

You might ask, where can I check my VMs from a central location to see which version of virtual hardware they run? Let's have a look.

Connect to your vSphere infrastructure via the vSphere Web Client. Then select your cluster (or host) and go to VMs. Click the signto expand them and then click Show/Hide Columns. Check the Compatibilitycheckbox to add this as a new column.

Add compatibility column

Add compatibility column

You can then drag this column to the left side for your convenience. Sort the VM hardware compatibility from the oldest to the youngest version to see which VMs might be running obsolete virtual hardware.

Click to sort by version

Click to sort by version

Note that you don't have to upgrade your VM's virtual hardware if you don't need the features present in this virtual hardware version. It is only optional.

Change the default virtual hardware compatibility level for new VMs ^

You can do this at the host or cluster level or at the data center level. Now if you run several clusters with different hardware, you'll need to do it on per-cluster basis.

In this case, simply right-clickyour cluster and change the setting at the cluster level.

Change the default to the version you need

Change the default to the version you need

You should consider a few conditions. For setting the default compatibility on the cluster, the cluster must contain hosts that are connected and not in maintenance mode.

Also, bear in mind that the default compatibility setting on the host overrides a default cluster or data center setting.

Lastly, the default compatibility setting on the cluster overrides a default data center setting.

As you can see, you must consider VM hardware compatibility and think of your entire infrastructure. Once you have VMs with the highest virtual hardware version and still have some hosts with older hardware that does not support a higher virtual hardware version, you won't be able to power on your VMs on those hosts or clusters.

Conclusion ^

As you can see, there is only a minimum difference between version 14 and 15, but when you're running some VMs on older virtual hardware and your underlying infrastructure changes drastically (such as for NVMe flash), you can benefit from the new features added in v14.

 

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