1.2. Why Should I Read This Book?If you've been doing system administration for some time, you may be asking yourself this question. There are many answers. Perhaps self-preservation is your primary motivator. You'd like to make sure you don't lose your job the next time a disk drive dies. Perhaps you've already got a decent backup system and you'd just like to make it better. Maybe you are looking for some new ideas about how to deal with upcoming backup and recovery needs. What follows are some of the reasons I think you should read this book. 1.2.1. SchadenfreudeSchadenfreude is a German word that means to take joy in the misfortunes of others. It's why we watch those weird videos on the Internet where some idiot tries to do something stupid and ends up hurting himself. Each of the sidebars in this book is a true horror story that really happened to someone I know. These are not urban legends or horror stories passed on from admin to admin. These are firsthand encounters with disaster. There's a schadenfreude element to reading these stories, of course. But each story also makes a point, and it was not just made up to make that point. The things that I warn about in this book really happen. This can be a very tough job if you are not prepared, so read closely. You might want to start by reading the sidebar "The One That Got Away" later in this chpater. It's the story of the defining moment in my career.
1.2.2. You Never Want to Say These Words"We lost only a few days' worth of data." In the sidebar "The One That Got Away," I said that we lost only a few days worth of data. I swore the day I said these words that I would never say them 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 about inexpensive backups 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 peopleask 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 is based on the premise that any data loss is unacceptable. Let me state that again for emphasis.
1.2.3. You're Curious About Open-Source Backup ProductsJust a few years ago, you could perform your backups with a few scripts and dump, tar, or cpio, or ntbackup. The demand for midrange computers grew astronomically, and the need for bigger databases, larger drives or filesystems, long filenames, and long pathnames grew proportionally. These large databases and filesystems started shipping, which then created a large market for commercial backup utilities, and one or two such products emerged; scores of others eventually followed. Some of these early products were just GUIs and volume management built on top of existing native backup utilities to provide enhanced levels 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, even proprietary, backup methods. They attempted to overcome the limitations that products based on dump and tar could not overcome. In recent years, the demand for centralized backup and recovery has also given rise to a number of open-source backup and recovery tools, six of which are covered in this book. The open-source backup market followed a pattern similar to the commercial products mentioned. The original open-source backup product, Amanda, is a wrapper around the native utility of your choice. BackupPC leaves data in its original format, and Bacula uses a custom format designed to overcome the limitations of GNU tar. There are now a number of choices in the open-source backup market. It's quite possible that one or more of the open-source products covered in this book can meet your backup and recovery needs. This book is currently the only resource that covers all of these tools in a single place. 1.2.4. You Want to Learn About Disk-Based BackupIf you haven't heard of disk-based backup or disk-to-disk-to-tape (D2D2T) backup, then it's time to turn off the digital video recorder (DVR) and pick up a trade magazine or two. (Of course, your DVR is nothing more than disk-based backup of your TV. And if you're occasionally making VHS tapes of your DVR shows, it's even a D2D2T system.) The use of disk in backup and recovery systems has exploded in the last few years, and it's really solving a lot of problems. Chapter 9 covers backup hardware and goes into much more detail about why disks have become a very attractive backup target. Here is a quick summary of some of those reasons:
Disk-based backups are also an extremely economical way to bring completely automated backups to small and medium businesses (SMBs). While a large tape library can be very inexpensive (on a dollars-per-gigabyte basis) and very expandable, the same is not always true of smaller libraries aimed at the SMB market. The big challenge is expandability. The less expensive a tape library is, the less expandable it usually is. (There are always exceptions, of course.) By comparison, some of the completely automated open-source backup products mentioned in this book can be used with a single disk drive costing less than $100. If you need to expand beyond that, just buy another disk and add it to your volume manager. You can also buy RAID controllers that allow you to start with one disk and add more as your needs grow. You can use this method to expand from hundreds of gigabytes to many terabytes of capacity. |