INF: Remote Sites and OS/2 Threads

  - Microsoft SQL Server version 4.2 for OS/2

The "Remote Sites" parameter, which is configurable via sp_configure, controls the number of simultaneous remote sites that can access the server (in the context of RPCs). It is documented that every remote site you set takes up two OS/2 threads, but it is not clear whether these threads are spawned when RPC activity takes place between two sites or whether they are spawned during SQL Server startup.

They are actually spawned during SQL Server startup and stay as long as SQL Server is running. So, if the value of "remote sites" is 10, then 20 OS/2 threads are used, regardless of whether or not RPC activity is taking place. So, this parameter must be set with caution. If it is inadvertently set too high, then there may not be enough threads for devices. This will result in a situation where SQL Server will not start because it has run out of threads to access the devices. In this case, the following error appears in the errorlog:

   OS/2 error 155: Cannot create another TCB