Database Dependancy Issue

15 Dec 2005 12:03 PM

lasmit

I have a very unusual problem which I would really appreciate some help
with, if anyone has come across something similar before.

Essentially we have three servers, a web server and two database
servers. There are several applications running on the web server and
the databases for each are distributed across the two servers. To even
the load it is necessary to move the database for one of the
applications to the other database server.

So,

Database Server A currently hosts the database
Database Server B is where the database should be moved to

The following steps were taken:

1) Detach database on Server A
2) Copy database MDF and LDF files to Server B
3) Re-Attach database on Server A in case rollback is required
3) Attach database on Server B
4) Change application to point at Server B
5) Test application - everything seems fine - can see data appearing in
Server B
6) Detach database from Server A

** The web application is now no longer able to connect to Server B. **

The following steps were then taken:

1) Reboot all three servers
2) Check that the connection string is definitely set in only one place
in the application

The web application is still unable to connect to Server B.

In a further peculiarity, as well as the Web Application there is also
a Windows service which accesses the same database. This is able to
connect to Server B fine, with or without the database on Server A
being attached.

Many thanks in advance

Lewis

15 Dec 2005 4:47 PM

lasmit

After looking further into the issue we were still unable to diagnose
the problem, so we setup a duplicate of the application on the web
server and did some tests. We could find no problems there and so we
went through with the swap again as we had done originally.

This time it worked fine.

All we can conclude is that something was cached somewhere in IIS and
that rebooting the machine did not clear this cache, but that the cache
cleared naturally after a period of time (it was 6 days between first
attempting the shift and then trying again).

If anyone has any thoughts or theories we would appreciate hearing
them, but in the mean time we just happy that it works :-)

Many thanks

Lewis