You can upgrade your liferay portal 6.1 to 6.2 by following the below steps:
1. Create a backup of your database (6.1) and take a copy of the document_library folder (6.1).
2. Copy the document_library folder(6.1) to the new folder(portal_path/data/ )
3. Start the server with a clean portal (6.2) and default configuration (Hypersonic SQL)
4. Close the server
5. Create a new database from the dump database(6.1)
6. Update ‘portal-setup-wizard.properties’ file:
- Set the connection to 6.2 database
- Add this property passwords.encryption.algorithm.legacy=SHA to be able to connect to your new portal.
- You can copy the other properties used in the old portal 6.1
7. Restart the server
8. Deploy all the portlets
9. Execute reindex
And that's it, you can enjoy your new 6.2 portal!