Yesterday, during a tentative to install SP1 on customer farm, I received a really stressfull failure message (below record on Upgrade.log):
[PSCONFIG] [SPManager] [INFO][8/22/2011 7:38:18 PM]: Upgrade Boot Strap starts. Initialized in Mode:InPlace, as MachineAdmin: True.
[PSCONFIG] [SPManager] [DEBUG] [8/22/2011 7:38:18 PM]: Detected v4 configuration database dsn: DataSource='"ColSQL08Web "';Initial Catalog=SharePoint_Config;Integrated Security=True;ConnectTimeout=15;Application Name="Microsoft SharePoint Foundation".
[PSCONFIG] [SPManager] [ERROR] [8/22/2011 7:38:32 PM]: SPManager.Initialize failed.
[PSCONFIG] [SPManager] [ERROR] [8/22/2011 7:38:32 PM]: Exception: A network-related or instance-specific erroroccurred while establishing a connection to SQL Server. The server was notfound or was not accessible. Verify that the instance name is correct and thatSQL Server is configured to allow remote connections. (provider: Named PipesProvider, error: 40 - Could not open a connection to SQL Server)
[PSCONFIG] [SPManager] [ERROR] [8/22/2011 7:38:32 PM]: atSystem.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception,Boolean breakConnection)
After that has been verify that SQL Connection was OK, that all SQL Services was started and that Windows Firewall was stopped, I was disappointed discovering that there was not solution other than remove this server from farm (this was just a test environment with three server).
Reading again Upgrade.log I noticed that Data Source name was strange, with "apexes" and a lot of blank space: now I knew because my Config_DB was dissappear!!!!!!!
I changed on Registry the correct key dsn [pay attention: this was a test environment!!!!] Computer\HKEY_LOCAL_MACHINE\Software\Microsoft\Shared Tool\Web Server Extensions\14.0\Secure\ConfigDB