When would I regenerate derivatives and/or datastreams for my objects?
You should regenerate your object's derivatives and/or datastreams in the event of an interrupted batch or single object ingest. Usually during an interrupted ingest, your object is ingested into the repository, but due to an error, the complete ingest process of creating derivatives and other datastreams is interrupted. Instead of deleting your object, it is quicker to regenerate the derivatives and datastreams in the repository.
How can I tell if I need to regenerate the derivatives and/or datastreams for my objects?
There are a number of ways you can tell if your object's derivatives and/or datastreams need to be regenerated. The most obvious sign is that your content will not display on your object page. For example, book and newspaper images will not display in the Internet Archive Book Viewer. You can also tell when your object displays a blank silver folder instead of a thumbnail.
Collection Objects have a silver folder by default until a thumbnail image is manually added to the objects TN datastream. You do not need to regenerate the datastream of Collection Objects that are missing the TN Datastream.
What are Derivatives?
Derivatives are copies of files in different formats that serve both archival and display purposes. In Islandora they are usually created when the asset is ingested into the repository. To learn more about deriviatives, see the "What are derivatives? Why do I care?" blog post on islandora.ca