FailOver causes "The underlying provider failed"

We implemented database mirroring for WCF and set up failover partner in connectionstring as following

....Data Source=10.0.13.21,1433;Failover Partner=10.0.13.31,1433; ...

10.0.13.21 - primary server
10.0.13.31 - secondary server

but somehow we get error:

the underlying provider failed

when the primary server is in failover state and the application is supposed to connect to secondary server. Everything works again after resetting IIS. Another strange thing is that the switch from secondary back to primary server is working but not from primary to secondary.

Anybo开发者_JS百科dy knows possible reason for this?

thanks in advance

I think you have to completely close your connection in the application and maybe do some retry code. Clearing connection pools may also be necessary. And also bear in mind that depending upon the size of the redo queues for the mirroring there may be a delay before the failover partner database is available again.

Here's a couple of links which I would read http://www.sqlskills.com/BLOGS/PAUL/post/A-SQL-Server-DBA-myth-a-day-(1130)-database-mirroring-failover-is-instantaneous.aspx

and http://technet.microsoft.com/en-us/library/cc917713.aspx