Kenneth Fisher makes a great point regarding backups:
I’ve said before that backups are at once one of the easiest things DBAs do, one of the most important, and one of the most complicated. Take a full backup, restore it. Pretty simple right? And yet it’s vital when accident or corruption require recovering data. And as simple as it can be on the surface, the more you dig, the more there is to know, and the more complicated it can become. Well, one of those complications is the backup of the backup files. I mean, assuming you are using native backups, that full backup is sitting on a drive somewhere, and hopefully, that drive gets backed up right?
Why? Well, for performance purposes you probably back up your databases locally. To a drive attached to the server. Now you may not, heck you could be backing up to Azure, but for the sake of this argument let’s say you are. Part of a careful disaster recovery plan is making sure you have access to those backups. I’ve heard stories of entire data centers going underwater (literally). You need to at least have a copy of your backups in a separate system, separate location from production.
The proliferation of S3/Blob Storage for “warm” backups and Glacier/Cool Blob Storage for “cold” backups has made it much cheaper to retain longer-term backups.