Unix Backup and Recovery

Step 2: Back Up Everything

This sounds like a given, right? It’s not. Certain types of data typically are excluded or forgotten. Many companies cut corners by omitting certain types of data from their backups. For example, by excluding the operating system from your backups, you may save a little media. However, if you find yourself in need of the old /etc/fstab, you will be out of luck. You may save some money, but you also may be putting your company at risk. It’s easier and safer just to back up everything. There also may be types of data that are forgotten completely. The most common mistake is to back up the data on a system but not to get a “picture” of what the system itself looks like in case you have to rebuild it.

Exclude Lists Good, Include Lists Bad

It is best to have a system that automatically backs up everything, except for a few explicit exceptions specified on an exclude list. If your backup system requires you to update an include list every time a new filesystem is added, you may forget or you may add it incorrectly; the result is that the filesystem does not get backed up. In a disaster, this means the data never comes back. This is why I prefer backup products that automatically back up all filesystems. (The concept of include and exclude lists is covered in Chapter 2.)

Databases

Backing up a database requires more work than backing up a normal filesystem. (Actual database backup procedures are covered in Part V of this book.) Theoretically, if you are backing ...