The actual recordings are stored on the drive. The DB with the guide data and scheduling info is stored internally in the tablo device.
If the drives dies, recordings are gone, replace drive (format etc) and show schedule stays intact. If you have a newer 2nd generation (at least) you can still watch live TV without a drive attached… so the tablo does function - you can see the show schedule data without a drive.
If your tablo die or you buy a new one - different things here. If you want to replace it, tablo has a migration process “Moving your Recording to a new Tablo” over simplified …it backs up the DB from the old tablo to drive, then “restores” it to new tablo.
If your tablo dies but not your drive - officially your SOL 
There are painstakingly ways to recover recordings depending how much it matters. tablo, unsupported - Recovering Show from good drive/dead tablo