Recently I posted about the upgrade of AHF/TAF from version 19 to 21 at Exadata and also for ODA. But with version 21 of AHF, some collections are made automatically and this can impact your space usage. Here you can see how to check this and disable/modify some of these.
The automatic collection for AHF/TFA is a feature that generates the diagnostic packages (to send to Oracle) when some specifics errors appear in the database. The collected errors follow some patterns like ORA-0600, ORA-07445, and several others. The basic idea can be seen in the official doc here and in the image below (retried directly from the official doc).