Data backup on Cloud can get damaged many ways. It can be deleted/overwritten by user's mistake or malicious attack on his or Cloud computer (or major Cloud hardware/software failure). To me internet storage is only acceptable as a second backup, that should be outside of the home anyway (fire, theft etc.). I keep music on HD drive and two HD backups (one outside of home) - total of 3 drives because it is possible that, while updating backup, something (like virus, controller failure, my mistake etc.) will damage both drives.
I update only one backup (stagger them) at the time and only after 5-10 new CDs added. It is very safe, since unpowered, disconnected drives in storage tend not to fail.
