Hi
We have an RDS farm with the following set-up (using Windows Server 2012 R2) to serve RemoteApps to our clients:
- Two RDS Gateways
- Four Session Hosts (24-physical processors and 512 GB ram each)
- User profile disks enabled
- One RDS Licensing Server
- Two RDS Broker Servers
The problem we are facing is that it seems like there's a "magic number" of about 450 connections (fluctuating between 445 and 455) per each Session Host.
Once this number is reached users start to report:
- General session slowness (slow update of Remote App window contents)
- Some users are unable to log in to their (new) session
- Some users are connecting but presented with "empty" screen
- Some users are getting (randomly?) disconnected
When the issue happens, based on performance counters, the CPU is in range of 30%, RAM has about 200 GB free.
Processor Queue length during the day is mostly within "<2 range", with ~30% of the time going higher up to 6 intermittently (not consistently), and with ~1.5% of the time being more than 10. (There's no continuous queue build-up) So our understanding that this is not a CPU/RAM limitation.
There were no limits on concurrent number of sessions set on Session Hosts as of SW side to my knowledge. Review of Application/System/RdpCoreTs Logs does not show anything really suspicious at the time the limit is hit, the errors/warnings in event logs do not correlate with timing of the problem.
We've been investigating this issue for a several weeks now and it's still absolutely unclear what could cause such limitation. Maybe someone experienced similar issues.
Any suggestions are welcome.