“We lost only a few days’ worth of data.” I swore the day I said that that I would never say those words again. From that day forward, I was convinced of the importance of backups. I never again assumed anything, and I began to study everything I could about backup technology. This book represents my attempt to compile what I have learned into a single volume, and it is written so that no one who reads it should ever need to utter the preceding statement. In my opinion, no amount of data loss is acceptable . I would also wager that you would be hard-pressed to find an end user who would feel much different. Whether it’s a spreadsheet that one person created, or a customer database representing hours, or days of sales invoices and the efforts of hundreds of people—ask the person who needs the data how much data loss they think is acceptable. Every statement, every opinion, every story, and every chapter in this book are based on the premise that any data loss is unacceptable. Let me state that again for emphasis.

If you’ve been doing backups for a while, you know that this hasn’t always been the case. Just a few years ago, if you couldn’t do it with dump, tar, cpio, and your standard database backup utilities, you couldn’t do it. The demand for midrange computers has grown astronomically in the last few years, and the need for bigger databases, larger filesystems, long filenames, and long pathnames grew proportionally. As things typically go in the backup world, large filesystems and huge databases were designed and shipped long before the utilities to back them up effectively were available. This created a large market for commercial backup utilities: one or two such products emerged, and scores of others eventually followed.

Many of these early products were just GUIs and volume management built on top of existing native backup utilities, and the GUI layers often added a significant level of functionality. Other companies felt that these native utilities had many limitations that could not be fixed without abandoning them altogether. Those companies chose to develop custom, or even proprietary, backup methods. They attempted to overcome the limitations that products that were based on dump and tar could not. Not all of these proprietary backup products did well, however, which sometimes left customers in the lurch with scores of backup volumes that could be read only by a deprecated product. Administrators who have been burned by a bad commercial utility often prefer a tool that uses native utilities.

Administrators can now choose from an almost dizzying number of backup products to fit a number of environments. Picking the right one can be difficult. Some are better than others, and some are simply a waste of money. However, there are very few systems or environments that are not being addressed with one product or another. Some solutions may require you to get closer to the bleeding edge of technology, and probably will cost quite a bit, but they are available. Sometimes options available with a particular backup product may even determine what platform is best for your very large database (VLDB) or Network File System (NFS) file server. This is a first in the industry: there are now hardware and software platforms that sell better because they are easier to back up. Instantaneous, up-to-the-minute restores that are invisible to the user are now available—for the right price.