Please refer to my other post: Team Foundation Server 2013 Update 4 - Completely crashing
The issue resolved itself, but basically TFS appeared to have triggered a state where SQL Server was unusable to the point an Administrator couldn't even restart the SQL services, and no one could connect to any of the databases. We had to restart the server, and connectivity was available for a short while before the issue reoccurred. All event logs related to TFS point to the fact it couldn't connect to the database, I couldn't find any indication as to why SQL Server went into that state.
Can you please help me troubleshoot what actually caused the issue (via my SQL Logs or Windows logs) so I can prevent it from happening again? What would you like for me to share?
Thanks, Jibba