Agent Unreachable After User Attempt to Connect Fails

[jmatz135]

We have Horizon View 7.1, and are using Windows 7 VMs, and are having issues with some of the agents going agent unreachable.  Basically what happens is occasionally a user will try to log in and the desktop will launch but the screen will be black for about 15 seconds and then the session will just close.  The user then typically tries to relaunch the desktop which then fails with an error that they are already connected to a session.  On the View administration side the desktop will actually show as the user is connected, but they obviously aren't.  Then after about 5-10 minutes the desktop will go agent unreachable.  If we restart the View Agent and the VMware Blast service on the desktop typically it will come back and the user could reconnect to it. 

Anyone have any ideas as to what might cause this?  We have a ticket open with VMware for about a month now, but haven't really gotten anywhere on it so I'm hoping someone has some ideas.

[auhank]

We've seen approximately this behavior with certain USB devices attached at the caller, although almost all our experience is with View 6 and earlier.   A recent case involved an older built-in card reader that presented as USB.  We blacklist by policy.

[jmatz135]

I've thought about that but this happens quite often with external users and we deny all access to usb for external users.  In fact the port that usb devices are on for external users isn't even allowed from external access, so I don't think it is that.  From my looking through the logs it looks to be an svga driver issue:

2017-08-02 14:10:02.567-0400 [ERROR] 0x125c svga::FlipFramebuffer: Fatal flip failure or too many flip failures. Might trigger safe mode and re-attach

I would think that this would be a hugely common issue for many people though if it was an svga driver issue?  Does no one use multiple monitors?  Does no one use the Blast protocol?