vSAN Stretched Cluster – Partition behavior changes

My good pal Paudie and I are back in full customer[0] mode these past few weeks, testing out lots of new and upcoming features in future release of vSAN. Our testing led us to building a new vSAN stretched cluster, with 5 nodes on the preferred site, 5 nodes on the secondary site, and of course the obligatory witness node. Now, it had been a while since we put vSAN stretched cluster through its paces. The last time was the vSAN 6.1 release, which led us to create some additional sections on stretched cluster for the vSAN Proof Of Concept…

VSAN 6.2 Part 9 – Replacing the witness appliance

There might be a reason in VSAN stretched cluster environments or in 2-node VSAN ROBO deployments to change the witness appliance. The one thing to keep in mind is that you must use a witness appliance that has the same on-disk format as the rest of the disk groups in the cluster. Right now, there is a 6.1 version of the appliance and a 6.2 version of the appliance, so make sure that you select the correct one. Replacing the current witness with a new witness is very straight forward, and the tasks can be summarized as follows: Deploy the…

VSAN Stretched Cluster – some possible warnings

We are hearing about a number of VSAN stretched cluster implementations going on at the moment, which is great news. I just set up such a configuration once again in my lab as we look at some various scenarios for the next release of VSAN. Now, for anyone looking at implementing VSAN stretched cluster, there is the VSAN 6.1 stretched cluster guide which should be your first port of call. However I noticed that once VSAN stretched cluster is implemented, you get a few warnings that you typically wouldn’t see in standard VSAN deployments. That is what I want to…

Step-by-step deployment of the VSAN witness appliance

In an earlier post, I described the witness appliance in a lot of detail. Using the witness appliance is VMware’s recommended way of creating a witness host. Ideally, customers should avoid building their own bespoke appliances for this purpose. Also note that the witness appliance is not a general purpose ESXi VM. It doesn’t store/run nested VMs, and it has no VM or HA/DRS related functions. It simply functions as a VSAN witness and plays no other role. In this post, I will take you through step by step instructions on how to deploy a witness appliance for either a…

A closer look at the VSAN witness appliance

As part of the Virtual SAN 6.1 announcements at VMworld 2015, VMware announced two new, eagerly anticipated features. The first of these is VSAN stretched cluster, allowing you to protect your virtual machines across data centers, not just racks. And the second is 2-node VSAN, which will be an excellent solution for remote office/branch office (ROBO) configurations. To allow these configuration to work, a dedicated witness host is required. For those of you already familiar with VSAN,  a witness component is used in the event of a split brain to figure out if the virtual machine objects have a quorum.…

Supported network topologies for VSAN stretched cluster

As part of the Virtual SAN 6.1 announcements at VMworld 2015, possibly the most eagerly anticipated announcement was the support for a VSAN stretched cluster configuration. Now VSAN can protect your virtual machine across data centers, not just across racks (which was achievable with fault domains introduced in VSAN 6.0). I’ve been hearing requests from customers to support this since the initial VSAN beta, so it is definitely a welcome addition to the supported configurations. The obvious next question is how do I set it up. Well, first of all, you will need to make sure that you have a…

VSAN 6.0 Part 1 – New quorum mechanism

vSphere 6.0 released yesterday. It included the new version of Virtual SAN – 6.0. I now wish to start sharing some of the new features and functionality with you. One of things we always enforced with version 5.5 was the fact that when you deployed a VM with NumberOfFailuresToTolerate = 1, you always had at least 3 components: 1st copy of the data, 2nd copy of the data, and then a witness component for quorum. In version 5.5, for a VM to remain accessible, “one full copy of the data and more than 50% of components must be available”. We…