Maximum number of sessions for RDSH Agent

Symptoms

The following kind of error is observed when attempting to launch a published item:

Cause

This error comes from Parallels Remote Application Server. It's generated when user is trying to create a new session by opening published resource on one of RDSH servers this resource was published from.

Max Sessions parameter is responsible for maximum amount of sessions allowed on RDSH servers in the Farm:

In some cases, this situation means that there is a server which has this parameter set to a lower value than other servers or Site Defaults.

This can be verified from RAS Console > Information tab:

The affected server will have less amount of active connections comparing to others.

NOTE: When there are a lot of RDSH servers in the Farm, the following log file on the server hosting Publishing Agent component can be used to track this event and find the exact RD Session Host where this issue is happening, however logs do not specify the exact RDSH when this issue happens for security purposes.

Here is how it looks in C:\Programdata\Parallels\RASLogs\controller.log:

[I 0E/00000000/T0FFC/P0638] 14-10-19 23:35:05 - Session login for user: ras02@ras, from IP: 11.111.11.11:58061 was successful.

[I 05/0000000E/T0FFC/P0638] 14-10-19 23:35:05 - Maximum amount of sessions reached.

[I 06/00000034/T0FFC/P0638] 14-10-19 23:35:05 - Resource LB User 'ras02' No Servers Available!

[W 06/00000002/T0FFC/P0638] 14-10-19 23:35:05 - Request for "#45" by User ras02, Client WORKSTATION, Address 11.111.11.11, was not served error code 14.

[W 06/0000000A/T0FFC/P0638] 14-10-19 23:35:05 - Failed to open "#45" Application for User ras02@ras, Client WORKSTATION, Address 11.111.11.11:58061 - (Error 14)

Alternatively you may notice the following warning from Parallels Remote Application Server Monitor:

in this case #45 is a published item ID in RAS Console:

In "Published from" tab you may find one or several servers, Server Group or All Server in Site specified:

For Server Group, please open RAS Console > Farm > RD Sessions Hosts > Groups and find the list of servers which should be checked:

For All Servers in Site and when there are dozens of servers in a Farm, it's easier to copy contents of RAS Console > Information to Clipboard:

Once pasted into Notepad ++ you may want to perform a regex search which is similar to this one:

Search text: (Sessions on|active connection)

NOTE: Using Information tab for checking active connections amount is viable only for Windows Server 2012 and above.

For a single Individual Server, please proceed to resolution steps described below.

Same steps should be used to check RDSH Agent Settings on a number of servers which do not belong to Server Group.

Resolution

Open RAS Console > Farm > RD Session Hosts:

Once properties are opened, switch to Agent Settings tab and check Max Sessions parameter:

NOTE: When parameters on this page are not grayed out, it means that they are set individually for this server and default settings are not being inherited.