> There are no problems (like corruption) if the server was power down during
> backup?

Since backup is an regular read-operation id should not cause corruption
when an power-fail does happen while backup. The backup file itself is
junk in case of an power-fail.

> When I restore the backup at a different location how I validate the
> restored backup? With gfix?

The gbak application should report an error if backup is not restorable.

> There is a “formula” to indentify that a Database NEED a backup/restore? I
> mean: If “A” is 50,000 bigger than “B” I need to backup/restore.

Usually there should be no reason for restore. Restore is only needed
when your database gets lost or damaged.

Elmar