Australian PC World - Sensible sessions save CD space

Sensible sessions save CD space

Tip
The price of recordable CD drives is plummeting, and blank 650Mb discs no longer cost the earth. That makes CD-R awfully intriguing for a variety of uses, many of which violate copyright laws. But two of the best applications for this storage mechanism are quite legal: archiving and backup.
CD-R drives are relatively fast. Even a first-generation CD-R drive will move more than 10Mb per minute, filling a disc in about an hour. And CD-R offers unbeatable reliability. Once you write to a CD-ROM disc, you can't change a byte. An unalterable record like that can be an advantage if, for example, you need to keep an audit trail.
But there's also an ugly side to CD permanence: if you don't want to fill a disc all at once, you must make multisession CDs. Multisession simply means you write to a given CD on more than one occasion or session. Each session requires not only a separate directory -- which means a few hundred kilobytes of overhead -- but also its own lead-in track, akin to the spiral between tracks of an old vinyl LP record. That lead-in track swallows a full 13Mb, so you lose at least that much with every CD session. If you back up a few files every day, CD space disappears faster than beer at a beach party.
The simple rule, then, is to be discriminating in how you back up. Make a full backup with a CD-R so you can reconstitute your system quickly if disaster strikes. Refresh the backup on a monthly schedule, or more often if your budget allows, but use a conventional system for incremental backups in the meantime.
This advice also applies to other CD-R uses. For example, to get the most out of every blank CD, record all your multimedia files in as few sessions as possible.
- Winn L Rosch

Category: Hardware
Issue: Dec 1996
Pages: 164