I am having two different applications , one works only with DB2 8.1 FP 2, whereas other application can handle DB2 8.1 FP12.
In the server, current version is DB2 8.1 FP2

So I am planning to install alternate fixpack of FP12, so that both the applications will work whilst getting advantages of higher version.

a) Can anyone suggest me, what are precautions, I need to take so that both the applications work post alternate fixpack installations?

b) Please let me know, the client accessing the DB from higher fixpack instance need to be upgraded? or need to bind?

Thanks in advance.

alternate fixpack is for servers
it is not recommended to have high fp level clients and lower server
it can be in the other way.
if client is upgraded, bind (db2cli,db2ubind) need to be done.

After you install the alternate fixpack, you update the instance you want to upgrade to the new fixpack level using db2iupdt and run the binds for each existing database in the instance (see the complete instructions in the readme file). When you run db2iupdt, you run it from the fixpack install directory that you want to use for that particular instance. So each instance is at a particular fixpack level.

So in your case, you will need two different instances, one at fixpack 2 and one at fixpack 12 (I would go with 14). Each instance will have its own port number and database name (for each database within the instance).

If both applications are using the exact same database, you must have 2 different databases (each in its own instance) to make this work. The data will not be kept in synch between the 2 databases (unless you some form of replication, which will likely be very nasty).

Thanks for the detailed reply.
Fortunately same database need not be in both instances.
I mean the application which needs lower FP level links to the separate database.

So I need to update the instance & database only once.

Thanks,
Siva