DAC issue

  • I cannot connect an SQL instance using DAC from either a local machine or from a remote machine. The error I came across is as follow.

    SQL Network Interfaces: An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for the port number [xFFFFFFFF].

    Sqlcmd: Error: Microsoft SQL Native Client : An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections..

    Sqlcmd: Error: Microsoft SQL Native Client : Login timeout expired.

    I checked the following spots

    DAC is enabled from the SQL Surface Area Configuration.

    Remote Admin Connection is enabled from sp_configure.

    SQL Server Browser is running.

    I checked the port number 1434. It is open and is listening.

    What did I miss here?

    Any input will be greatly appreciated.

  • Hi,

    Can you execute this sp_configure 'remote admin connections', 1;

    And DAC port is assigned dynamically it trys to connect using TCP on port 1434 and it is failing it tries to check with other ports. I think you have to execute that and try and if that does not work try connecting with

    sqlcmd –Stcp:

    Thanks

    Chandra Mohan N

    [font="Verdana"]Thanks
    Chandra Mohan[/font]

  • Books online states these restrictions:

    Restrictions

    Because the DAC exists solely for diagnosing server problems in rare

    circumstances, there are some restrictions on the connection:

    To guarantee that there are resources available for the connection,

    only one DAC is allowed per instance of SQL Server.

    If a DAC connection is already active, any new request

    to connect through the DAC is denied with error 17810.

    To conserve resources, SQL Server 2005 Express Edition does

    not listen on the DAC port unless started with a trace flag 7806.

    The DAC initially attempts to connect to the default database

    associated with the login. After it is successfully connected,

    you can connect to the master database. If the default database

    is offline or otherwise not available, the connection will return

    error 4060. However, it will succeed if you override the default database

    to connect to the master database instead using the following

    command:

    sqlcmd –A –d master

    We recommend that you connect to the master database with

    the DAC because master is guaranteed to be available if the

    instance of the Database Engine is started.

    SQL Server prohibits running parallel queries or commands with the DAC.

    For example, error 3637 is generated if you execute either of the

    following statements with the DAC:

    RESTORE

    BACKUP

    Only limited resources are guaranteed to be available with the DAC.

    Do not use the DAC to run resource-intensive queries (for example.

    a complex join on large table) or queries that may block.

    This helps prevent the DAC from compounding any existing server

    problems. To avoid potential blocking scenarios, if you have to run

    queries that may block, run the query under snapshot-based isolation

    levels if possible; otherwise, set the transaction isolation level to

    READ UNCOMMITTED and set the LOCK_TIMEOUT value to a short

    value such as 2000 milliseconds, or both. This will prevent the DAC

    session from getting blocked. However, depending on the state that

    the SQL Server is in, the DAC session might get blocked on a latch.

    You might be able to terminate the DAC session using CNTRL-C but

    it is not guaranteed. In that case, your only option may be to restart SQL Server.

    Do any of these match your case ?

    Johan

    Learn to play, play to learn !

    Dont drive faster than your guardian angel can fly ...
    but keeping both feet on the ground wont get you anywhere :w00t:

    - How to post Performance Problems
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  • Thank you so much for the input above. I have tried all you recommended. It still does not work now, however.

  • what software level are you on ?

    select @@version

    You are using a login that is member of the sqlserver administrators group, right ?

    Johan

    Learn to play, play to learn !

    Dont drive faster than your guardian angel can fly ...
    but keeping both feet on the ground wont get you anywhere :w00t:

    - How to post Performance Problems
    - How to post data/code to get the best help[/url]

    - How to prevent a sore throat after hours of presenting ppt

    press F1 for solution, press shift+F1 for urgent solution πŸ˜€

    Need a bit of Powershell? How about this

    Who am I ? Sometimes this is me but most of the time this is me

  • I used a sa account.

    My SQL Server version is SQL 2005 enterprise edition with SP2.

  • Please look thru sql logs to find the port DAC is listening to and mention that port number wth the server name while taking DAC connection.

    MJ

  • I did check. BOL states that DAC check default port first. If the default port does not exist, it will automatically check the open port for DAC.

  • Out if interest is your environment a clustered server configuration?

  • i am also facing the similar problem in my sql server clustering configuration . it was not allowing me to open the surface area configuration wizard after changing the remote machine name as virtual machine name its allowing to open the surface area window now but its not allowing to modify the settings in the surface area configuration wizard ...its giving the error message you cannot modify the surface area configuration for clustering services ...

    Thnks in Advance.

  • With clustering stuff, many thing must be managed using cluster administrator!

    What are you looking for ? (With regards to instance management)

    Johan

    Learn to play, play to learn !

    Dont drive faster than your guardian angel can fly ...
    but keeping both feet on the ground wont get you anywhere :w00t:

    - How to post Performance Problems
    - How to post data/code to get the best help[/url]

    - How to prevent a sore throat after hours of presenting ppt

    press F1 for solution, press shift+F1 for urgent solution πŸ˜€

    Need a bit of Powershell? How about this

    Who am I ? Sometimes this is me but most of the time this is me

  • ALZDBA (7/4/2009)


    With clustering stuff, many thing must be managed using cluster administrator!

    What are you looking for ? (With regards to instance management)

    i want enable the DAC remote acces from SAC

  • did you try this in SSMS:

    EXEC sp_configure 'remote admin connections', 1;

    GO

    RECONFIGURE;

    GO

    Johan

    Learn to play, play to learn !

    Dont drive faster than your guardian angel can fly ...
    but keeping both feet on the ground wont get you anywhere :w00t:

    - How to post Performance Problems
    - How to post data/code to get the best help[/url]

    - How to prevent a sore throat after hours of presenting ppt

    press F1 for solution, press shift+F1 for urgent solution πŸ˜€

    Need a bit of Powershell? How about this

    Who am I ? Sometimes this is me but most of the time this is me

  • ALZDBA (7/5/2009)


    did you try this in SSMS:

    EXEC sp_configure 'remote admin connections', 1;

    GO

    RECONFIGURE;

    GO

    Yes .. i have enabled that by executiing that query already ..but issue is i could not able to modify the anything by using the sac wizard in sql server clustering setup.

  • Did you change the SAC connection from localhost to the logical server name of your sqlserver instance ?

    e.g. mysqlserver\myinstance you should connect to mysqlserver.

    Johan

    Learn to play, play to learn !

    Dont drive faster than your guardian angel can fly ...
    but keeping both feet on the ground wont get you anywhere :w00t:

    - How to post Performance Problems
    - How to post data/code to get the best help[/url]

    - How to prevent a sore throat after hours of presenting ppt

    press F1 for solution, press shift+F1 for urgent solution πŸ˜€

    Need a bit of Powershell? How about this

    Who am I ? Sometimes this is me but most of the time this is me

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