Hi, I've got 1 instance serving 2 databases. (aix_5.3/db2_8.2 32bit). Memory management on a 32bit db2 on aix is ... let call it a challenge and one way to wring some extra memory to the bufferpools is to create an extra dedicated instance and move 1 of the databases to that other instance.
I know it can be done and it should be simple. I know I've read about it in the past, but now I get google-hits pointing to other directions (sanjai never shared how he did it Moving DB from one instance to another instance).
Anyone got a nice link on how to accomplish such a task and are there any pitfalls I should avoid?

You can allocate up to 2GB per database (db shared memory) in a 32-bit instance on AIX. It doesn't matter if 2 databases share one instance or are in separate instances.

Are you sure it's as simple as that? Memory belongs to a process, not a database, and all databases in one instance are managed by the database manager process of that instance...

I remember the discussion we had before...
DB2 V9.5 - STMM errors


I believe each db shared memory can be up to 2GB in a 32-bit instance on AIX.

There is more. It is all about a "db2 content manager" system wich uses the LS & RM databases (library server & resource manager). Because of the many connections I've enabled the connection concentrator. Fine for the LS, but not required for the RM. Another reason to split the 2.
It is not clear documented but this featuere seems to have effect on db2-sort behaviour (same effect as INTRA_PARALLEL). Suddenly I must take the possibility of "shared sorts" into account . After the split I can ignore the shared-sort config for the RM db again.

If you want to move it to another instance, then you can use backup/restore or db2relocatedb:
The db2relocatedb tool

I am writing my "plan of approch" now and I want to use the db2relocatedb tool. I wonder who should execute this command?
- root?
- the current instance owner?
- the new instance owner?

root copies/moves the files from the current location to the new location and changes ownership of the files to the new instance owner.

the new instance owner runs the db2relocate command to change the configuration files

HTH

Sathyaram