DB2 v11 – Java Version Shipped with Database

Here is documentation for DB2 for i on i5/OS V6 R1.

Here is specific to DB2 itself.

Here is specific to DB2 SQL.

Upgrade via restore is usually supported for databases two versions down, so to move from DB2 6.1 to DB2 10.1 (current today) you'd need to move to DB2 8.2 first, then to DB2 9.5, then to DB2 10.1. There are many things that have changed between all these versions, so it's very unlikely that the process will be smooth. Your best option would be to extract the database DDL statements and data, then create a new DB2 10.1 database and load data into it.