Use relative pathnames when backing up
One of the most useful features of the modern operating systems' file systems is the availability of both absolute and relative pathnames. One of the major differences is that an absolute pathname assumes it is starting from the root directory while a relative pathname figures out where it is in the file system before it starts to execute. In Unix, relative pathnames begin with a directory name or a ./ while an absolute pathname begins with a /. Absolute pathnames are somewhat more efficient since the file system has to parse relative pathnames to use them.
When backing up a Unix system, the best practice is to use relative pathnames. Using absolute path names can produce all kinds of problems. For example, you may have to use a boot floppy to start the system after a hard disk failure. If you have specified the absolute path names, the restore will try to write all the archived files to the floppy.
EST Inc. has a white paper on the most common mistakes in backing up Unix and Linux systems on its Web site. The paper is oriented toward the company's BRU backup software, but the information is generally useful.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
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Unix Backup and Recovery
Author : W. Curtis Preston
Publisher : O'Reilly & Associates
Published : Nov 1999
Unix Backup and Recovery provides a complete overview of all facets of Unix backup and recovery, and offers practical, affordable backup and recovery solutions for environments of all sizes and budgets. The book begins with detailed explanations of the native backup utilities available to the Unix administrator, and ends with practical advice on choosing a commercial backup utility.