Data Backup Systems

Something I am very interested in is Data Backup Systems.

The cases I want to prevent are:

• When non-volatile memory fails (be sure your hard disk drive will fail, so do something about it)
  
• When a computer virus or malicious user (or just human error) corrupts data.

The solution needs:

• Be able to backup my data and only backup URLs of data that can be easily downloaded from the Internet, not wasting backup space.
  
• Data stored in multiple places separated physically from one another (to prevent both being damaged at the same time) using a remote backup service.
  
• Data stored to be only read, so no computer virus or malicious user can corrupt backups.
• Data stored incrementally to be able to quickly and easily see changes in time of the data.
• Be able to get any file at any point past in time.
• Be totally automated and non-intrusive.
• Do a perfect snapshot of every backup. Backups should never be corrupt.
  
• Encrypted, so data can be sent to untrusted external storage.
  

Current solutions:

• Use always RAID1 (at least). Setting up software RAID in Linux is extremely easy and works exceptionally well. With Linux you just need two hard drives (no need for them to be identical) and you do not need a RAID controller if you use software RAID as it works great and it may be even faster than hardware RAID. I will help you if you have any problems with it.
• Set up automatic encrypted backups to off-site storage (like a web server).
• Mac OS X users may be able to use Apple Time Machine but it lacks true network backup as backing up just to another local hard drive is not the best option.