vSAN Direct Configuration is a new feature released via Update 1 for vSphere 7. It provides, according to VMware, an alternative option for modern stateful services to interface directly with the underlying direct attached storage (DAS) and have optimized I/O performance.

We have already reported in detail about new features in VMware vSAN 7 and walked you through the configuration of vSAN file services, allowing you to create SMB or NFS shares for your company environment. I invite you to check the post about vSAN and native file services and quotas.

The difference between traditional vSAN storage and vSAN Direct is basically that for workloads that need resiliency (VMs), vSAN provides security and data resiliency via traditional vSAN storage and Failure to Tolerate (FTT) storage policies.

For apps that do not need resiliency, since they work in clusters and have resiliency within their own architecture (Kubernetes, Minio, and Dell, for example), vSAN Direct does not double that resiliency but instead provides direct access to the data control plane for those applications and thus slightly better performance.

VMware vSAN Direct Requirements ^

  • Unclaimed disks—This feature needs some unclaimed disks on each host within a vSAN cluster. So, if you have already created your disk groups and have no other disk groups available (unclaimed), it might be necessary to simply evacuate the data from an existing disk group and recreate it by specifying the vSAN Direct option. If you are able to add more disks to your host and create another disk group, this would be the second option for achieving the configuration.
  • vSAN License—You'll need a VMware vSAN license installed and activated for that particular cluster. But you already knew this if you were going for a vSAN-based cluster, right? If you're new to VMware and if you have a Standard or Enterprise license, this license itself does not entitle you to create and configure a vSAN cluster. You need a vSAN license.

There are no other requirements.

vSAN Direct Setup Steps ^

The setup is fairly simple. When you create a new disk group, simply select vSAN Direct from the drop-down menu. Let's detail the steps further, as well as the creation of a new VM storage policy via the vSphere client.

First, connect to your vCenter server and select your vSAN cluster. Then select Configure > vSAN Disk Management > Claim Unused Disks.

Claim Unused Disks for VMware vSAN

Claim Unused Disks for VMware vSAN

Then click the Claim Unused Disks button. It will launch a pop-up window where we can choose vSAN Direct from the dropdown list in the Claim For column.

Note: In order to create a disk group, you need to select one disk for the cache tier and one or more disks for the capacity tier.

In our case, we have only one capacity disk. Let's do this for the cache disk and for the capacity disk; otherwise, the assistant won't allow you to continue.

Claim Unused Disks for vSAN Direct

Claim Unused Disks for vSAN Direct

In my case, the disks added to the hosts have identical capacities for both the cache tier and the capacity tier. While the system figured this out automatically, we can also assign those disks manually, host-by-host. Here is the view.

Claim Unused Disks for vSAN Direct manually

Claim Unused Disks for vSAN Direct manually

vSAN Direct does not have the same icon as the traditional disk group. In fact, it does not have an icon at all. By selecting the vSAN Direct disks, you can see the individual disks with their details down in the lower pane. You can see the drive type, that they were claimed as vSAN Direct, and their capacity.

Check the vSAN Direct and individual disks

Check the vSAN Direct and individual disks

Once the disks are claimed, we are able to create a new storage policy that will allow us to use them.

Go to Shortcuts > Select Policies and Profiles.

Select Policies and Profiles

Select Policies and Profiles

Then click the Create a New VM Storage Policy button and add a meaningful name and description. In our case, simply naming the policy "vSAN Direct" will do.

New VM storage policy for vSAN Direct

New VM storage policy for vSAN Direct

Then, on the second page of the wizard, select the Enable tag-based placement rules option. This allows us to assign tags to vSAN Direct Storage.

Enable tag based rules

Enable tag based rules

Then, on the third page of the wizard, select vSANDirectStorage from the Tag dropdown list.

Add tag based usage option

Add tag based usage option

So, the final screen looks like this.

Add a tag based usage option like this

Add a tag based usage option like this

The next screen simply shows us the review and indicates that all the devices that we want to use for vSAN Direct are listed here. You can click Next and Finish to close the assistant.

The new storage policy should appear in the list. You can select the policy and see which devices are compatible.

vSAN Direct Storage Policy and all associated storage devices

vSAN Direct Storage Policy and all associated storage devices

Final words ^

With vSAN Direct activated on your vSAN cluster, you will be able to use any of the upcoming releases of Dell, Minio, or Cloudian solutions that are able to leverage vSAN Direct. As for now, those applications are not GA just yet.

vSAN Direct is a new construct within VMware vSAN that enables a high-performance data path for applications that are able to consume local storage devices on vSAN hosts directly. The monitoring and health of those devices are monitored via standard VMware vSAN monitoring tools.

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Applications consuming the vSAN Direct storage are aware of vSphere infrastructure operations, such as maintenance mode and vSphere upgrades, where a rotating maintenance mode for all hosts is set in order to upgrade the whole cluster. Those applications can react to those interruptions by either being evacuated or temporarily deleted and recreated once the maintenance mode is finished, all without the manual intervention of the operator.

1 Comment
  1. Chris 7 months ago

    Test Update with vSAN direct on my test cluster - with vSAN Direct, vSphere 7.0U2, I was able to add 1 SSD from each node to form vSAN Direct Storage disk group. Does not look like it needs cache / capacity like regular VSAN. 

    I am adding in k8s / Tanzu and thinking utilizing vSAN direct or testing with it would be ideal. 

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