How to configure the Virtual SAN observer for monitoring/troubleshooting

There have been various blog posts on the topic of configuring the Virtual SAN observer on both Windows and Linux by Rawlinson Rivera and Erik Bussink. I like to keep things in a single location and document them for my own use so I figured I would do a write-up for yellow-bricks.com. First of all, what is the Virtual SAN / VSAN observer? One of our engineers (Christian Dickmann) published an internal blog on this topic and I believe it explains what it is / what it does best:

You will also find VSAN datastore as well as VM level performance statistics in the vSphere Web Client. If however you are the kind of guy who wants to really drill down on your VSAN performance in-depth, down to the physical disk layers, understand cache hit rates, reasons for observed latencies, etc. then the vSphere Web Client won’t satisfy your thirst in vSphere 5.5. That’s where the VSAN observer comes in.

So how do I enable it? Well I am a big fan of the vCenter Server Appliance so that will be my focus. Just a couple of short steps to get this up and running luckily:

• Open an ssh session to your vCenter Server Appliance:
  • ssh root@<name or ip of your vcva>
• Open rvc using your root account and the vCenter name, in my case:
  • rvc root@localhost
• Now do a “cd” in to your vCenter object (you can do an “ls” so see what the names are of your objects on any level), and if you do tab it will be completed with your datacenter object:
  • cd localhost/Datacenter/
• Now do a “cd” again, the first object is “computers” and the second is your “cluster”, in my case that looks as follows:
  • cd computers/VSANCluster/
• Now you can start the VSAN observer using the following command:
  • vsan.observer . –run-webserver –force
• Now you can see the observer querying stats every 60 seconds, and as mentioned you can stop this by doing a <Ctrl>+<C>

Fairly straight forward right? You can now go to the observer console using:

• http://<vcenter name or ip>:8010
  The below is what it should look like (Thanks Rawlinson for the nice screenshot)
  

Now one thing that is important to realize is that everything is kept in memory until you stop the VSAN observer… So it will take up GBs after a couple of hours. This tool is intended for short term monitoring and troubleshooting. Now there are  some other commands in RVC that might be useful. One of the commands I found useful was “vsan.resync_dashboard”. Basically it shows you what is happening in terms of mirror sync’ing. If you fail a host, you should see the sync happening here…

I also found “vsan.vm_object_info” very useful and interesting as it allows you to see the state of your objects. And for the geeks who do not prefer to see the pretty graphs the observer shows, take a look at “vsan.vm_perf_stats”.