Section 2.1. Don t Skip This Chapter

2.1. Don't Skip This Chapter!

The casual reader might assume that this chapter is an introduction to basic backup concepts. While that is, in fact, the purpose of this chapter, it is also true that many seasoned administrators are unfamiliar with the ideas presented here. One reason for this is that administrators find themselves constantly being pulled away from "mundane" activities like backups for things that are thoughtto be more "important," such as installing new servers and figuring out why systems are running slowly. Also, administrators may go several years without ever needing to perform a restore. The need to use your backups on a regular basis would undoubtedly change your ideas about their importance.

I wrote this book because backup and recovery has been my primary area of emphasis for several years, and I would like to share the lessons I've learned from this focused activity. This chapter provides an overview of how your backups should work. It also explains many basic yet extremely important concepts upon which any good backup plan should be based, and upon which all implementations discussed in this book are based.

2.1.1. The Impossible Job That No One Wants

Would anyone reading this book say that losing data is OK? I don't believe so. Then why do we treat backups so lightly? Sometimes I feel like Rodney Dangerfield when I'm arguing for better backups"I tell ya, I don't get no respect, no respect." Backups often aren't considered during systems design. When a new server is purchased, does anyone ask for the impact on the current backup methodology? Some IT departments do not even have control over the purchase of new systems, because they are sometimes bought by other cost centers. Have you ever tried to explain to another department manager why his terabyte-sized database server isn't going to get backed up to the standalone, gigabyte-sized tape drive that came with it?

Another often-overlooked issue is backup personnel. Have you ever tried to find the person in charge of backups? It's often an extra duty that gets passed around, in a manner similar to the way my sister and brother and I argued over whose turn it was to wash the dishes. If you are lucky enough to have a dedicated person, it's usually the most junior person in the company. I know, because that's how I got my first job. In fact, that's how many people get their first jobs. How can we give such low priority to something so important? Perhaps we should change that. Will one book change this long-standing hiring tradition? Probably not, but maybe it will help. At the very least, if the person in charge of backups has this book, that person has a complete guide to accomplishing the immense task that lies ahead.

What's the big deal, you say? With modern computer systems and reliable disk drives, why are backups still so important? Because computers still go down, that's why. Also, companies are placing more reliance than ever on computers functioning reliably. I don't care how good your Unix vendor is or how reliable your disk drives are or even if you have Dogbert himself as your network administrator, systems go down. Murphy's Law thrives in computer systems. Not only will your computer systems go down occasionally, but they will do so at the time most inconvenient to you and your customers. At that moment, and that moment will come, it is the job of the backup person to replace the data on the disk or disks that have stopped the show. "How long will it take?" is a typical question. The only acceptable response is "it's already done."

Who wants to be the person who messed up the restore and caused the customer database to be offline for three extra hours? Who wants to be the person who has to send a memo to the entire company saying that any purchase orders entered in the last two days have to be reentered? Who wants to be the person who has that in mind every day as they are checking the results of last night's backups? If you do your job well, and no data is lost, you are just doing what you're supposed to do. If you mess up, you're in big trouble. Who wants that job? No one, that's who.

You're reading this book because you've got the impossible job that nobody wants. Whether you've been doing it for a while or have just started down the backup road, you can see that the task that lies ahead is immense. The volume of data is tremendous, the nature of the data changes constantly, and the utilities at your disposal never seem to be up to the job. I know because I've been there. I've spent months trying to implement "solutions" from operating systems and database products that weren't ready. I've seen companies spend money on expensive commercial utilities, only to buy the wrong utility for their application. I've watched newer and bigger servers roll in the door without a single backup drive among them. I've also spent long nights and weekends in computer rooms trying to recover data in a "reasonable" amount of time. Unfortunately, "reasonable" is defined by the end user who has no idea how difficult this job is.

There are now solutions to almost every backup problem out there. If you run a small shop with just a few systems, all of which run the same operating system, there's a solution for you. If you work in a huge shop with hundreds of boxes in the various flavors of Unix, Linux, Windows, and Mac OS, or just a few multiterabyte databases, there's a solution for you. The biggest part of the problem is misinformation. Most people simply do not know what is available, so they either suffer without a solution or settle for an inferior oneusually the one with the best salesperson. The six important questions that you have to continually ask yourself and others are why, what, when, where, who, and how:

Why?

Why are you protecting yourself against disaster? Does it really matter if you lose data? What will the losses be? What different types of data do you have, and what is the value of each type?

What?

What are you going to back up, the entire box or just selected drives or filesystems? What operating systems are you going to back up? What else, besides normal drives or filesystems, should be included in a backup?

When?

When is the best time to back up your system? How often should you do a full backup? When should you do an incremental backup?

Where?

Where will the backup occur? Where is the best place to store the backup volumes?

Who?

Who is going to provide the hardware, software, and installation services to put this system together?

How?

How are you going to accomplish it? There are a number of different ways to protect yourself against loss. Investigate the different methods, such as off-site storage, replication, mirroring, RAID, and the various levels of protection each provides. (Each of these topics is covered in detail in later sections of this book.)