Chapter 18. BackupsOperating securely means having your data available reliably. Bugs, accidents, natural disasters, and attacks on your system cannot be predicted . Often, despite your best efforts, they can't be prevented. But if you have backups, you can compare your current system and your backed -up system, and you can restore your system to a stable state. Even if you lose your entire computer ”to fire, for instance ”with a good set of backups you can restore the information after you have purchased or borrowed a replacement machine. Insurance can cover the cost of a new CPU and disk drive, but your data is something that in many cases can never be replaced . [1]
Backups can be very simple, such as a Zip disk in your desk drawer , or they can be exceedingly complex, such as a set of redundant drives located on opposite sides of town, connected by fiber channel, with a robotic tape changer that automatically cycles the tapes according to a predefined schedule. Alas, Unix backup systems are generally less sophisticated than those for Windows systems and somewhat more difficult to use. Many Windows-based systems, for example, will automatically create a special "restore floppy" that you can use to automatically restore all of your computer's files onto a brand new hard drive. Few Unix systems provide such recovery tools. On the other hand, most Unix backup systems operate in a network-based environment, and many of them are free. This chapter provides basic coverage of principles and programs for backing up Unix systems. An in-depth discussion of backup and restore systems would require another book ”for this, we recommend W. Curtis Preston's book, Unix Backup & Recovery (O'Reilly). |