Section 15.1. Can It Be Done?

15.1. Can It Be Done?

Think about database backups from a big-picture perspective, and compare them to filesystem backups. There are a number of good backup utilities on the market now. Why aren't there just as many for database backups? There is certainly a demand for them.

One of the reasons is the complexity of the task. In order to release a database backup product, a company needs to consider several factors:

Multiple moving targets

How do you get a database to hold still? Have you ever tried to take a picture of 100 people? Designing a backup utility for a database is very hard because you have to "take a picture" of hundreds of files all at once.

Interrelationship between the files

A database backup program needs to understand all the database elements and how they relate to each other.

Necessity to work with the database engine

This is essential. If the database understands that you are running a backup, it can help you. If you don't interface with the database, you'll be backing up blind.

The size of the job

How do you get more than a terabyte of data to a backup drive in one hour? That's what some of the backup requirements are!

Recoverability versus cost

You need all of the preceding, but you don't want to mortgage your house to get them.

Differing levels of automation

Different customers want different levels of automation. Some want everything managed by the library while others would rather do it themselves.

With these kinds of requirements, is there any hope of getting utilities that are up to the challenge? The answer is "Yes!" Database companies have finally recognized that backup utilities do have an effect on the overall sales of a database engine. They have finally started producing good utilities that interface with other commercial backup products. Vendors have even taken an active lead in making sure that customers use a utility that works properly on both the backup side and the restore side. Now that there are decent backup utilities, though, you have another problemconfusion.