Why Cloud PACS
If your acquisition computer is the only store then if it fails recovering your images may significantly delay restoring image acquisition ability.
Backing up onto an external disk rarely works – equipment fails, nobody checks the back up, back up software stops working, data format is not compatible.
Keeping a back up on site doesn't reduce the risk of losing studies in the case of burglary, fire, flood or misplacement.
Accessing images off-site – if possible – will slow due to the asymmetric upload/download speeds. Upload speed are a fraction of your download speed.
There is a hidden cost to managing and maintaining any information system.