During the week I was at a customer site that is using vSAN 6.2 as foundation for their upcoming virtual desktop infrastructure (Seems like 2016 is really really the year of the VDI). I love vSAN and believe that at the moment it’s a great fit for many dedicated use-cases within the virtualization field.
During some load- & failover tests of the vSAN installation I realized something regarding the IO-queues within the vSAN-stack and to be honest, I am not quiet sure what the risks, mitigations and therefore the correct actions are.
We open a VMware ticket in parallel, but if you have any more in-depth knowledge about this topic, please let me know since this might be interesting to more of people (since the number of vSAN implementations is increasing).
Since the integration of flash/SSD in the performance/cache tier of vSAN the performance is great compared to classical HDD-based solutions.
To ensure a good performance level Duncan Epping and Cormac Hogan talked about the queuing topics within some blog posts or the offical vSAN troubleshooting reference manual (great document btw.).
If you have a black-screen on the vSphere console (no matter if using .NET client, Web-Client, Remote-Console, etc.) typically the following things help you out:
- Having the correct port opened between your client and the ESXi host where the virtual machine is running on (TCP: 903)
- Correct working DNS: Your client must be able to lookup the ESXi FQDN
For sure there are many more things… most of them are well documented nowadays… so check them out.
There might be another reason if you use Windows 10 or Windows 2012 R2 (Not sure how it is in the older versions) where the symptoms (a black screen) might be similiar, but the problem is not vSphere related (even though it seems to be).
After fixing a failed SSD of one of my lab-hosts I had some minor issues with my vCenter. Whenever I logged on into it I received this error.
“ An error occured while sending an authentication request to the vCenter Single Sign-On server – An error occured when processing the metadate during vCenter Single Sign-On setup – null.”
fair enough I checked the :5480 VAMI of my PSC and vCenter and the vCenter showed me the SSO was not initialized.