With vSAN 8.0 U1 a lot of new features and enhancements are introduced. There are many blog posts out there describing the long list of enhancements, but in this post, I want to focus on HCI Mesh or Disaggregated vSAN specifically. (Also read this post by Cato!) For this feature, which in the UI is referred to as “Datastore Sharing”, there are 3 key enhancements introduced in vSAN 8.0 U1. There are enhancements for both the Original Storage Architecture (OSA), as well as the Express Storage Architecture (ESA).
With vSAN 8.0 the initial version of ESA was launched, and it did not support the use of Datastore Sharing. Starting with vSAN 8.0 U1 though, vSAN ESA is now also capable of sharing its storage with other clusters in the environment. To be more precise, a vSAN ESA cluster can now mount the datastore of another vSAN ESA cluster. What we also support is a “compute only” cluster mounting the vSAN ESA datastore remotely. So for those planning on implementing vSAN ESA, I think that is a very welcome enhancement!
For OSA there are also two enhancements for Datastore Sharing. The first I want to discuss is cross-vCenter Server datastore sharing. This feature is especially useful with customers who have a larger estate and are managing multiple clusters via different vCenter Server instances. You simply now have the option to connect the vCenter Server instances from a storage point of view, and then you can simply select the remote datastore in the cluster managed by a different vCenter Server instance. Let me just show you how this actually works in the next demo.
The second enhancement for OSA specifically is support for Stretched Cluster configurations. Starting with vSAN 8.0 U1 it is now possible to mount a vSAN Datastore which is stretched across locations. Your “client” cluster” can be “stretched”, “standard”, or compute-only even. We support all of those combinations. On top of that, the interface enables you to specify which location should be paired with which location, or fault domain. In other words, if you look at the diagram below, I can ensure that the hosts in Site A connect via the “local” network” to the remote datastore as part of Site A. This avoids IO traversing the intersite link, which can make a big difference in terms of latency and available bandwidth for other I/O etc.
I can imagine that the concepts are difficult to grasp without seeing the vSphere Client, so I spend some time in the lab to create a demo for you that walks you through the steps of how to configure this. In the lab I created a vSAN Stretched Cluster, and a standard cluster, and I am going to mount the vSAN stretched Datastore to the host in the standard cluster. Enjoy!
With Stretched cluster support for mounting vSAN datastore, does that also include 2-node stretched clusters ?
Comment and Question – during some testing we found that when vCenter is upgraded that our vSAN licensing have to be upgraded as well ( we upgraded vCenter from 7 to 8 and had to provide vSAN 8 licensing as the old licensing changed to temporary licenses). The hosts were ESXi 7. Since VSAN is embedded into vSphere… what advantage is it to have your hosts running ESXi 7.x? You don’t get any of the VSAN 8 enhancements with vSphere 7.x ….or am I missing something.
There is no advantage, I would always recommend to upgrade both vCenter and ESXi.
Yes, 1+1+1 stretched clusters are also supported with vSAN 8.0 U1, 2-node ROBO however are still not afaik.
By 2-node ROBO you mean with direct-connect vSAN, without physical switches ? So the limit is with direct-connected vSAN data for 2-node configurations. So you need to have physical switches in the configuration.
Is there a practical limit to the ratio of hosts in server clusters vs. client clusters. For example with a stretched OSA VSAN in 6+6+1 with all flash storage, not withstanding the maximum number of connected hosts (128?) is the a practical limit on the number of client cluster hosts, before performance impacts would be noticeable?
Would that be possible to use 2-node vSAN Cluster (vSAN Adv.) as an storage extension for stretched cluster (vSAN Ent.)?