Unix Backup and Recovery

How Do I Read This Volume?

If you’re a system administrator long enough, someone eventually will hand you a volume and ask “Can you read this?” They don’t know what the format is, or where the volume came from, but they want you to read it. Or you may have a very old backup volume that you wish you could read but can’t. How do you handle this? How do you figure out what format a volume is? How do you read a volume that was written on a different machine? These are all questions answered in this chapter. There are about 10 factors to consider when trying to read an unknown or foreign volume, half of which have to do with the hardware itself—whether or not it is compatible. The other half have to do with the format of the data. If you are having trouble reading a volume, it could be caused by one or more of these problems.

Prepare in Advance

If you’ve just been handed a volume and need to read it right now, ignore this paragraph. If you work in a heterogeneous environment and might be reading volumes on different types of platforms, read it carefully now. Reading a volume on a platform other than that on which it was created is always difficult.

In fact, except for circumstances like a bad backup drive or data corruption, the only sure way to read a volume easily everytime is to read it on the machine that made it. Do not assume that you will be able to read a volume on another system because the volume is the same size, because the operating system is the same, or even if the utility ...