CD Backups with Easy File Access

Bryan Smith

CD drives are common components, which makes CD media ideal for both self-backup/restores done by users and point backups by systems administrators. But what is the optimal CD backup approach? In this article, I will introduce the back2cd script, which maximizes CD capacity while preserving CD’s inherent random-access advantage.

CD Recorder Optional

Creating a CD of files does not require a CD recorder on the same system because CD backup is a two-step process. The first and most involved step is mastering (i.e., creating) the CD image. A CD image is then used in the second step, recording (i.e., burning) to CD media. The back2cd script (Listing 1) handles the first step (mastering) irrespective of a CD recorder on the system. (All Sys Admin magazine listings are available here.)

Mastering files into a single CD image file is analogous to archiving files into a single tar, cpio, or zip file. Archiving stuffs files and their attributes (meta-data) into a single file (archive). As with tar or cpio, there is a defined standard format for CD images. The ISO9660 CD standard defines a data track format known as “Yellow Book”, commonly represented as a CD image file with a .iso extension. back2cd is built around the mkisofs (make ISO filesystem) program, included or available for most UNIX systems (and standard in Cygwin).

Recording a CD image is then analogous to un-archiving. The CD recorder software un-archives the files from the single .iso file onto CD media. Thus, the resulting CD is a replica of the files, their hierarchy, and their meta-data (assuming they are preserved during the mastering process).