Yellow Bricks

by Duncan Epping

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vSAN Health Check fails on vMotion check

On Slack someone asked why the vMotion check for vSAN 6.6 Health Check was failing constantly. It was easy to reproduce when using the vMotion IP Stack on your vMotion VMkernel interface. I went ahead and tested it in my lab, and indeed this was the case. I looked around and then noticed the following in the vSAN 6.6 release notes:

vMotion network connectivity test incorrectly reports ping failures
The vMotion network connectivity test (Cluster > Monitor > vSAN > Health > Network) reports ping failures if the vMotion stack is used for vMotion. The vMotion network connectivity (ping) check only supports vmknics that use the default network stack. The check fails for vmknics using the vMotion network stack. These reports do not indicate a connectivity problem.

Workaround: Configure the vmknic to use the default network stack. You can disable the vMotion ping check using RVC commands. For example: vsan.health.silent_health_check_configure -a vmotionpingsmall

I guess that clarifies things, so I figured I would test it. Here’s what it looked like before I disabled the checks:

I used RVC to disable the checks, let me show two methods:

vsan.health.silent_health_check_configure -a vmotionpingsmall /localhost/VSAN-DC/computers/VSAN-Cluster

Note that you will need to replace the “VSAN-DC/..” with your cluster and datacenter name. This disables the vMotion ping test. The other is running this command in interactive mode, that will allow you to simply enter the number of the specific test that needs to be disabled. It will list all tests for you first though.

vsan.health.silent_health_check_configure -i /localhost/VSAN-DC/computers/VSAN-Cluster

The vMotion tests are somewhere half down:

44: vMotion: Basic (unicast) connectivity check
45: vMotion: MTU check (ping with large packet size)

And of course this doesn’t only apply to the vMotion tests, with vSAN 6.6 (vCenter 6.5.0d) you can also disable any of the other tests. Just use the “interactive” mode and disable what you want / need to disable.

VSAN Health checks disabled after upgrade to vCenter 6.0 U2

Yesterday at the Dutch VMUG I was talking to my friend @GabVirtualWorld. Gabe mentioned that he had just upgraded his vCenter Server to 6.0 U2 in his VSAN environment, but hadn’t upgraded the hosts yet. Funny enough later someone else mentioned the same scenario and both of them noticed that the VSAN Health Checks were disabled after upgrading vCenter Server. Below a screenshot of the issue Gabe saw in his environment. (Thanks Gabe)

vsan health checks disabled

So does that mean there is no backwards compatibility for the Healthcheck, well yes and no. In this release we made our APIs public, William Lam wrote a couple of great articles on this, and in order to deliver a high quality SDK backwards compatibility had to be broken with this release. So if you received the “health checks disabled” message after upgrading to vCenter Server 6.0 U2, you can simply solve this by also upgrading the hosts to ESXi 6.0 U2. I hope this helps.

** Update March 23rd **

Please note that ESXi 6.0 Update 2 is also a requirement in order to enable the “Performance Service” which was newly introduced in Virtual SAN 6.2. Although the Performance Service capability is exposed in vCenter Server 6.0 Update 2, without ESXi 6.0 U2 you will not be able to enable it. When trying to enable it on any version of ESXi lower than 6.0 U2 the following error will be thrown:

Task Details:

Status: General Virtual SAN error.
Start Time: Mar 23, 2016 10:55:35 AM
Completed Time: Mar 23, 2016 10:55:38 AM
State: Error

Error Stack: The performance service on host is not accessible. The host may be unreachable, or the host version may not be supported

This is what the error looks like in the UI:

Here you go, VSAN 6.2 GA!

We’ve been talking about if for a while now, but last night the moment finally arrived… VSAN 6.2 aka vSphere 6.0 Update 2 was released. I am not going to go in to any level of depth here, as I have written many posts on the subject of VSAN 6.2 already, and so has my friend Cormac, the best start is probably this blog though. You can read those if you want to get the nitty gritty details, or nerd knobs as apparently some like to call it. (I prefer to call it a healthy level of curiosity, but that is a different discussion.) Here is what is in 6.2:

  • Deduplication and Compression
  • RAID-5/6 (Erasure Coding)
  • Sparse Swap Files
  • Checksum / disk scrubbing
  • Quality of Service / Limits
  • In mem read caching
  • Integrated Performance Metrics
  • Enhanced Health Service

Now that is not it, there is also some new stuff in vSphere 6.0 Update 2, one which I feel is very welcome and that is the Host Client! A full HTML5 based client which comes as part of your ESXi host, very useful if you ask me! Also two-factor authentication was added for the Web Client, several enhancements to the vSphere APIs for IO Filtering and support for different databases for vCenter etc.

Okay, lets stop blabbing, start your download engines, find your bits here: