In the last years, file systems have been one of the main research topics for mainstream operating systems. Microsoft has been developing their new WinFS as a new generation storage system for Longhorn, but it has been recently dropped due to maturity problems. As an upper level over NTFS, WinFS would provide a a framework where the semantic meaning of the information would be more important than the place where this information is stored: in other words, you could do complex queries on your data, or save these searches as virtual folders that are live views of your files (in the same way you do in Spotlight).

All these new features reflect a deep change in the way our information is stored in the Hard Disk. While some years ago the only information needed was the name of the file and some basic attributes, metadata is becoming more and more important for users. The main meaning of an MP3 file, for example, is not only represented by the basic name of the file, but also by the author or the year of the song.

Following this path, file systems are slowly becoming another form of database where semantic information is stored with the file data. WinFS, Spotlight or Beagle provide this functionality as an upper level to the underlaying file system, keeping a database that is feeded from metadata obtained from our files and synchronized when these files change.

Searching with Beagle in Linux

The next step is the inclusion of temporal data in this file system database. Mac OS X Leopard will include the first software that keeps record of previous versions of our files. Time Machine lets you navigate back and forth in time in your file system, seeing snapshots of how your hard disk was one week ago, for example, and restoring previous versions just with one click.