In the question Need Help Troubleshooting Sql Server 2005 Deadlock Scenario there was a suggestion of using
DBCC TRACEON (1204, -1) to trace deadlocks globally.
When reading about this command in BOL it states that it should only be used while users or applications are not concurrently running statements on the system. Does it mean that we must be in singleuser-mode when enabling this trace-flag? And in addition, why is it required and is it important to follow the advice? (Just seems a bit hard to follow in a production system that is always running.)