Failover Not Work When Principal Server Is Down

Hi,

Here is my testing environment:

Database server: SQL Server 2005 Developer Edition with SP1
Application: An application developed by Visual Studio 2005 using C# (.Net framework 2.0) and ADO .Net 2.0.

Principal server: computerA
Mirror server: computerB
Witness server: computerC
Mirroring mode: High availability with auto failover

Connection String:
Data Source=computerA;Failover Partner=computerB;Initial Catalog=test_mirroring;Persist Security Info=True;User ID=sa;

Code used for failover:

while (true)
{
thisDataSet = new DataSet();

try
{
thisConnection = new SqlConnection(connectionString);
thisAdapter = new SqlDataAdapter(SQL, thisConnection);
thisAdapter.Fill(thisDataSet, name);
break;
}
catch (SqlException e)
{
thisConnection = null;
thisAdapter = null;
thisDataSet = null;
}
}

Test Case:

(Part A) At the beginning of the test, computerA was in principal role. I started my testing application and connected to computerA without any problem. Then I disconnected the connection of computerA to the network by unplugging the network cable of computerA. The failover of database from computerA to computerB was carried out without problem. computerB was in principal role at that time. The application was pending for about 45 seconds and running again without problem. Then I re-connected computerA to network and it became the mirror server. computerB was still in principal role. Up to this point, all works fine, but the problem was coming next. (Part B) I disconnected computerB from network, database failover occurred, computerA became principal again. But my application cannot switch the database connection to computerA and then kept pending. Then, I re-connected computerB to network. It was surprised that the application switched the database connection to computerA successfully at that point.

My questions:

1. I think Part B is abnormal, isn€™t it? The application should be able to failover from computerB to computerA, because it works fine when failover from computerA to computerB.
2. Is there anything wrong in my code leads to the abnormal behavior of the application in Part B.
3. How can I achieve Part B? Any suggestion or idea?


Thanks for your attention.