Hi , When I tried to stop db2 instance , I had the error 'database is in use'. Then I listed the application and couldn't see any. Then I displayed the IPCS and cleaned them. Then I tried to stop the db2 instance again. I am getting the following errors :
a)SQL6048N A communication error occurred during START or STOP DATABASE MANAGER processing ( For all partitions)

b) SQL1025N The database manager was not stopped because databases are still active

When I display the IPCS again then I can see many Message ids(m) and Queues(q) for the instance. Should I need to cancell this individually or is there better way forward to resolve this issue ?
Thanks.

Applications may be connected to other partitions, may they not?

You should also check that the the db has not been activated using the activate db command. You can issue "list active databases" to check. If a db is listed with zero applications currently connected, then use the deactivate db command to deactivate it. The only time you might need to remove IPC resources is when an application(s) won't go away with the force application / db2stop force command. In this case, issue db2_kill followed by ipclean and then check for / remove all remaining processes / IPC resources associated with this instance (on all physical nodes)

If you have more than one physical server (in a multi-partitioned database) you need to run IPCS on each server.

Thanks everyone. Finally it stopped. I managed to start without any issue. But I can see some warning messages. Just for curiosity what are these refring to ?

2010-09-11-16.35.44.757931+060 E88189A387 LEVEL: Warning (OS)
PID : 3350664 TID : 1 PROC : db2sysc 4
INSTANCE: db2test1 NODE : 004
FUNCTION: DB2 UDB, oper system services, sqloqualifydir, probe:30
CALLED : OS, -, unspecified_system_function
OSERR : ENOENT (2) "No such file or directory"
DATA #1 : File name, 0 bytes

It should also print the file name. You can ignore this message if there are no errors logged at around the same time.