Unix Backup and Recovery

Restoring with the restore Utility

While writing this section, one phrase kept coming to mind. “The time to take Dramamine is too late to take Dramamine.” The same thing applies to learning how to use the restore utility. You need to become very familiar with the various ways in which you can use restore to retrieve data from a backup created with dump. If you are in the midst of a critical restore as you read this, don’t worry—this section is organized with that scenario in mind and includes every trick available in restore.

Tip

This next section assumes that you know the volume was made with dump and that you know its block size. If you do not know this information, please skip ahead to Section 3.10 near the end of this chapter.

Is the Backup Volume Readable?

To make sure that you know the format and block size of a tape, try listing its table of contents. The following command produces the table of contents of a volume created with dump :

$ restore tbfy 
                  block_size device-name

For example, to read the table of contents of a dump tape (made with a blocking factor of 32) on /dev/rmt/0cbn, issue the following command:

$ restore tbfy 32 /dev/rmt/0cbn

If that works, then the rest is easy. (If not, read Section 3.10 later in this chapter.

Blocking Factor

Sometimes, however, as mentioned earlier in this chapter, dump can write in a blocking factor that restore cannot read. This problem is usually very simple to get around. Once again, you will need the block size in which the volume was ...