Tablo's auto-delete feature will keep a minimum amount of space free on your hard drive at all times. This ensures that your hard drive never reaches 100% storage. For all Tablo DVRs except the Tablo DUAL 64GB and the Tablo DUAL 128GB, this feature is off by default.
When enabled, its logic works as follows:
The oldest unprotected recordings will always be deleted first.
The Tablo will determine how much space to keep free depending on the size of your attached hard drive. The rules work as follows:
Drives at a size of 750 GB or less will always keep 2 hours per tuner (based on your recording quality) free at all times.
Drives at a size of 1TB or less will always keep 3 hours per tuner (based on your recording quality) free at all times.
Drives at a size of 4TB or less will always keep 4 hours per tuner (based on your recording quality) free at all times.
Drives larger than 4TB will always keep 6 hours per tuner (based on your recording quality) free at all times.
For an estimate on how much drive space each recording can take on its respective quality, visit this article:
http://support.tablotv.com/hc/en-us/articles/201445336-How-much-space-does-Tablo-require-to-record-a-program-
Note: If you are using the Tablo 4th Gen product and its internal storage, the Auto-Delete feature works slightly differently on this variant to maintain free space.
Specifically, the ‘extend live recordings’ setting will add an additional 30 minutes to a live recording. On other Tablo types, this can record up to a maximum of 2 hours.
However, if you’d like to add up to 3 extra hours of recording time to any program, you can do so via the airing/series recording options.