You don't need to ask the system manager to restore files. When you do need a file, you can get it right away, without waiting. What's more, you can recover any version you want, with one command, and get the file back immediately.
Sounds great, doesn't it?
All you need to do is use either SCCS (Source Code Control System) or RCS (Revision Control System). SCCS comes standard on most System V UNIXes; RCS is available on many BSD-based systems, and is also available on the CD-ROM.
Of course, SCCS and RCS won't protect you from a disk crash, but they can protect you from many cases of accidental file deletion or corruption. These tools were developed to manage multi-person development projects, ensuring that only one person has write access to a file at one time, and making it possible to go back to any previous version of a file. But as it turns out, they are handy for any user who has important files that change frequently.
Article 20.13 tells how to use SCCS to protect your files. Article 20.14 does the same for RCS.