There has been a lot of discussion in the past around supported topologies for 2-node vSAN, specifically around where we can host the witness. Now my good pal Duncan has already highlighted some of this in his blog post here, but the questions continue to come up about where I can, and where I cannot place the witness for a 2-node vSAN deployment. I also want to highlight that many of these configuration considerations are covered by our official documentation. For example, there is the very comprehensive VMware Virtual SAN 6.2 for Remote Office and Branch Office Deployment Reference Architecture…
Sometime back I wrote an article that described what happens when an object deployed on a vSAN datastore has a policy of Number of Failures to Tolerate set to 1 (FTT=1), and multiple failures are introduced. For simplicity, lets label the three components that make up our object with FTT=1 as A, B and W. A and B are data components and W is the witness component. Let’s now assume that we lose access to component A. Components B & W are still available, and the object (e.g. a VMDK) is still available. The state of these two components (B…
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…
Our friends over at Pearson and VMware Press have informed us that the second edition of the Essential Virtual SAN book (that I wrote with Duncan Epping) is now available for pre-order on Amazon. It looks like it will be available on June 13th, but VMware Press have told us that they will do what they can to pull the date in a little closer. This new edition covers all of the new features added to Virtual SAN, up to the latest (yet to be released) VSAN 6.2. Here’s some blurb on the new edition, which gives a little insight…
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…
This is an exercise that we ran through in our lab environment, and we thought that the steps would be useful to share here. By way of introduction, our 4 node cluster is split into a 2+2+1 configuration, where there are 2 ESXi hosts on site A (VLAN 4), 2 ESXi hosts on site B (VLAN 3), and a third site, site C (VLAN 80), hosting the witness appliance (nested ESXi host). All sites are connected over L3. In other words, static routes are added to each of the ESXi hosts so that ESXi hosts on site A can reach…
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…