Client-side problem with mirroring

Hi!

I posted this on the adonet forum but didn't get any response so I might as well post it here. Hope anyone can help me.

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I have set up mirroring and trying to get it to work from my .NET
application. Mirroring seems to work ok.
When I do a manual failover the witness is updated properly in the
sys.database_mirroring_witnesses table so it seems to be configured
correctly. I also can shutdown the master database and the mirror takes over.

My application is configured with Server set to my master database and
FailOverPartner to my mirror database.

If I am connected to the master database and do a manual fail-over all my
attempts to communicate with the database fail with an exception, even after
repeated retries.
(System.Data.SqlClient.SqlException: A transport-level error has occurred
when sending the request to the server. (provider: TCP Provider, error: 0 -
An existing connection was forcibly closed by the remote host.).)

If I do a manual fail-over and restart my application it connects to the
mirror database and everything is working. If I now do a manual fail-over I
get the same exception, but after a few retries it connects to the master
database.

The field Connection.Datasource always shows the master database regardless
if it's connected to the mirror.

What am I doing wrong? Is this how it's supposed to work?

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I have been pulling my hair over this problem and I just can't get it to work.

I'm using SQL Server Authentication to access the database and I can connect
to the master when it's acting as principal and I can connect to the mirror
when it's acting as principal, but when doing a fail-over, manual or shutting
down the master server it never tries to connect automatically to the mirror
even if it's changed role to principal.

Do the client need access to the witness in any way?

I'm using version 2.0.50727 of System.Data.dll.

I'm wondering if when you say "master database", you are refering to the system database called master or the principal database. It isn't clear. So I am going to assume that you mean "principal" database when you say "master" database, but your comments are very confusing. Also remember that Principal and Mirror are roles, it is better to state Server A and Server B and the role they are currently in. Also, when you say master database, everyone in the world thinks you are refering to the system database called "master," which cannot be mirrored. We'll get it figured out. :)

"My application is configured with Server set to my master database and
FailOverPartner to my mirror database."

You mean Server set to Server A and Failover_Partner is set to Server B, correct? You should not be putting database names in where there should be server names...

"Do the client need access to the witness in any way?"

No.

"I'm using version 2.0.50727 of System.Data.dll."

Can you verify that you are using the same System.data.dll as in this KB? http://support.microsoft.com/kb/912151/

"but after a few retries it connects to the master
database."

By retries, do you mean that the application is processing the network error and issues a reconnect?

Thanks,

Mark