Time Machine is a truly good idea: It helps you automatically back up everything on your system and restore earlier versions of files at any time. (1)
It’s much more than just files – it’s data. Time Machine includes an API for applications to backup/restore data – such as contacts or browser favorites. Unlike other backup software or OS features, you can individually restore a contact deleted in the past using the software that created the contact, Address Book, and Time Machine. This is not possible with any technology Microsoft has shipped or has announced for Vista. The API can be used by applications to support incremental backups of data inside of the application’s data store – instead of the entire data store (think Personal Folders.pst).
But this was a great idea over three years ago when Microsoft first added it to Windows Server 2003 as Volume Shadow Copy (VSC, or “Previous Versions” to end users). (1)
Snapshots are a more advanced technology (2) that are technically better than a file copy for point in time backups of an entire disk volume. So, Microsoft added a better technology (than file copy) to Windows Server 2003 & Windows Vista. Time Machine uses a “file system event notification system” (2) to determine which files to copy the files to the backup device. Since snapshots require source volume, and the idea is to backup to an external volume or network location, snapshots (on their own) are not a viable solution.
That’s why Microsoft is shipping both Previous Versions and Windows Backup as part of Vista. A user can rely on Windows Backup to restore all of the applications and data or selected file types. Previous Versions represents a convenient way to restore files by right-clicking the file, selecting properties, and browsing through the list of every snapshot taken of the file. Windows Backup is slow, performs full and incremental backups, and will notify the user when they should create a new, full backup. Previous Versions is fast and data is stored on the source volume along with the actual data without annoying user prompts. Windows Backup is a traditional backup application, and traditionally, most people do not use these applications.
(1) Apple Mac OS X Leopard Preview: Who’s the Copycat Now?
(2) Time Machine and the future of the file system