Allen Kinsel - SQL DBA

SQL Server, SQLPASS, and other random things

Whose got my DAC?

By Allen Kinsel, 7 days ago

What is the DAC?

The Dedicated Admin Connection, Commonly called the DAC is used to manage SQL Server when a regular connection wont succeed.  Here's what SQL Books Online (BOL) has to say about the DAC «This diagnostic connection allows an administrator to access SQL Server to execute diagnostic queries and troubleshoot problems even when SQL Server is not responding to standard connection requests.»

DAC Errors

Occasionally, while troubleshooting SQL servers in a large environment, especially one thats managed from many different geographic locations you could come up with this error, if more than 1 person is using the DAC.  It should also be noted this only happens if you have remote DAC enabled in your environment

Error 17810

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Using Aliases with SQL Server

By Allen Kinsel, 1 month and 18 days ago

Even an old dog can learn new tricks

Where Can I get a dog like this?
I had an Aha! moment recently.  For my entire career as a DBA I have generally considered aliases for connections a workaround for bad behaving applications.  Whenever someone said «alias» my mind immediately heads to SQL Server client configuration aliases which I try to avoid if at all possible (since they are configured on each client)  It never snapped to me until recently that DNS aliases may be a good solution to a few problems  we're currently experiencing.

For disaster recovery reasons, as well as for manageability reasons we have decided to start using DNS aliases for every application connection to database servers.  This should allow us to have the luxury of moving databases from server to server without having to reconfigure multiple applications which would normally be a whole process in itself since the code was already migrated to production which is locked.

Using DNS aliases should also allow us to swap highly important applications over individually to a remote datacenter, which could have less computing power, without having to switch every application and thus kill the performance of that standby server.


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