Facebook used an encryption key per user for their backups. For deletion they just delete the encryption key which makes the data unreadable. There was an artic

Facebook used an encryption key per user for their backups. For deletion they just delete the encryption key which makes the data unreadable. There was an article years ago about their cold storage infrastructure, Blueray discs if I recall. https://www.datacenterfrontier.com/cloud/article/11431537/inside-facebook8217s-blu-ray-cold-storage-data-center https://www.datacenterfrontier.com/cloud/article/11431537/in...