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In the third part of the VDI troubleshooting series, unlike the last two parts, I want to talk about client-side connection problems. For instance, if there is a dedicated subnet of IP addresses for Zero Client devices, then incorrect setup or miss-configuration of routing settings can be the reason for the connection problem between VDI clients and servers. Same way, wrong VLAN configs (ID, subnet, Inter VLAN Routing) can be the main reason for the trouble. So I provided a checklist of "What to do if you have a problem with your Horizon connection servers?"


1. Check the correctness of Zero/Thin client's communication infrastructure (routing, switching, etc) to the VDI servers (Connection Server, Security Server)

2. Check network connection between Connection Server subnet and deployed Virtual Machines of Desktop Pool, if they are separated. Of course, logically there is no need to connect their dedicated Hosts/Clusters to each other, so you can have separate ESXi Clusters, one for Desktop pools and another for VDI Servers.

3. Investigate the vCenter Server is accessible from Connection Server and also its related credential.

4. If you have a Composer Server, check it's Services. So many times I saw the Composer Server service does not start after a server reboot, while it's automated and no warning/error event has been reported. Also, you need to check the ODBC Connection between Composer Server and its Database.

5. Investigate installed View Agent state inside the Desktop Pool's VMs. If you need to provide client redirection to the desktop (without the presence of Connection Server) View Direct Agent is needed too.

6. A TCP connection on port 4001(non-SSL)/4002(SSL-based) between Desktop's View Agent and Connection Server must be established, It's required for connection and you can check it by running netstat -ano | findstr "4001".

7. Review the User Entitlement for provided Desktop Pools, maybe there is a mistake especially when you add AD Groups instead of AD Users. (also check them, are they still available or assigned to the other users?)

8. Type of Virtual Desktop provisioning is also important. Except for Full Clone, on Linked Clone and Instant Clone models, you need to check the status of Virtual Desktops in Inventory\Resources\Machines of the View Admin web page.

9. If there is an interruption in connected sessions, you need to review their states in Inventory\monitoring of the View Admin web page.

10. For the last Note: DO NOT FORGET TO CONFIGURE EVENT DATABASE! I had encountered too many Horizon View deployment that did not configure any event database, so in troubleshooting situations, we had NOTHING to know really what happened.

I hope it can be helpful for you all buddy...

Link to the original post on my personal blog: Undercity of Virtualization: VMware VDI (Horizon View) Troubleshooting - Part III