Informatica and DataStage both are ETL tools, which are used for data acquisition process, Nothing but ETL the main difference between Informatica and DataStage is for Informatica the repository (container of meta data  is database-meta data is stored in database for data stage the repository is file-meta data is stored in file before going to ETL Informatica & DataStage will check the repository for meta data here accessing a file is more faster than database because file is static but data is more secure in data base than file-data may be corrupted in file hence finally we can conclude that data stage will perform faster than Informatica but when it comes to security issue Informatica is better than DataStage