SQL Server Error: Communication Link Failure

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SUMMARY

Error occurs while adding, updating or deleting Watch Items in WebWatchBot Manager.

SYMPTOMS

Errors can occur consistantly or rarely.

The Windows Event Viewer, Application Log, contains an entry with the error containing the words "Communication Link Failure" or

Microsoft OLE DB Provider for ODBC Drivers [Executing Non Query] Error: -2147467259 Msg: Unspecified error 
Description: [Microsoft][ODBC SQL Server Driver]Communication link failure

CAUSE

The machine WebWatchBot is installed on is overloaded and does not have enough resources to run both WebWatchBot and SQL Server or WebWatchBot by itself. The communication link between WebWatchBot and SQL Server is broken during a database transaction because of this. When WebWatchBot communicates with SQL Server, a timely response is expected. If SQL Server cannot process its own internal workload and communicate back to its clients, it will break the communication link intentionally or unintentionally to conserve resources and prevent further overload.

SQL Server is typically bound by memory constraints that are effected by the size of the WebWatchBot database and the number of concurrent queries.

RESOLUTION

There are three recommended approaches to resolving this issue (in order of effectiveness):

  1. Increase physical memory allocated to the machine, to ensure that SQL Server has enough resources to handle the database demands of WebWatchBot.
  2. Reduce the size of the WebWatchBot database. Refer to KB: How to Reduce the Total Amount of Data in the WebWatchBot Database
  3. Move SQL Server to another dedicated machine and/or move the WebWatchBot database to that machine. Refer to KB: Moving WebWatchBot's Database from one SQL Server Instance to Another