Changing platforms in Oracle 10g leads me to two paths. One, using Data Pump (expdp) as suggested. Or, using Transportable Tablespaces (TTS). I like the TTS option for a 1.5 TB database since you can simply FTP your tablespace's datafiles to your new server and plug them in to the new database. The majority of the time is spent FTP'ing the files. With a database this size, Data Pump requires to you export the database's contents, FTP the dump file to the new server, and then import the dump file to the new database. This can be time-consuming.
Refer to the Oracle documentation for information on TTS.
The only downside of TTS is that it only copies tables and indexes. Any stored procedures, views, sequences, etc. need to be re-created in the destination database.
This was first published in August 2007