If the user complaint you that application is running very slow. As

a DBA where do you start your work ???how do you find where exactly

the problem is???

As for me I used the perfmon, profiler and activity monitor to find out where the problem is. To detect I/O bottleneck use the Perfmon and monitor the processor, CPU, memory and Disk I/O. Use the Activity monitor to detect blocking processes that occurs on the database (which is the common problem). Use the profiler to detect Queries/batch that are causing the slow performance of the database.

After logshipping configured,users are connecting secondary

server...how can you disconnect them?

Before the logshipping job restore the transaction logs it should kill all processes that are currently running on the database otherwise the restoration will fail and it will return an error like "Cannot hold exclusive access to the database.."

Log file size increasing ,..even after logshipping configured??

what could be the reason?

database log file will eventually increase in time depending on the frequency of data modification on the database

what are the configuration changes before and after installing sql server service pack???

see microsoft for details...