August 12th, 2006

Noone enjoys making frisbees out of their blank CD or DVD media. Disc burn errors render discs completely unusable, and can cost you a lot of money as well as time. For some strange reason (Murphy’s law?) when duplicating, mechanical and/or software failures always seem to occur when there’s a tight deadline to hit. This adds even more unneeded tension to an already stressful situation.

Buffer underrun is the most common problem when creating CDs or DVDs. Underrun occurs when the buffer supplying data to the burner is emptied before all the requested data gets written. The main cause of a buffer underrun is a system interruption. Luckily, such interruptions can be avoided. Whether you’re making copies yourself, a client, or training a customer to do so, these six tips and tricks will help keep the copies coming:

1. Avoid interruptions. Before you burn any copies, make sure all programs that could interrupt the operation–including screen savers, e-mail clients, anti-virus updates, and fax software–are turned off. If there is a network connection, unplug it, too.
2. Keep target files together: If the files you want to burn are scattered across the hard drive, the burning software may have trouble finding them quickly enough to send smoothly to the burner. To prevent this common problem, keep all related files in the same folder. Or, even better, reserve a partition on the hard drive for storing disc images. And, of course, never copy across a network.
3. Create a disc image: Most disc-burning software gives you a choice of either creating a disc image of the files to be burned or burning them on-the-fly. An image is simply a single file that contains all the files you want to burn. An image aggregates the data for the burn process and doles it out with the best speed, thus reducing underruns at the burners. One alternative is for the program to pick up files from all over the disk, which involves diffent times to seek and deliver the information that might be interrupted by disk fragmentation or some machine action. Yet another alternative is to copy disc to disc, but this is slow.
4. Defrag often: When you save a file to the hard drive, the data is written to blank parts of the disk, which are not necessarily close together or even in the same sector. As a result, a file’s data can be fragmented across the disk. Later, when the user tries to copy the file, the software has to find and reassemble all the fragments, and this can slow things down. Defragmentation–better known as defragging–attempts to consolidates each file into a single, contiguous space for fast access. On Windows XP, you’ll find the defrag tool by clicking on Start, then Control Panel, then Performance and Maintenance, then “Rearrange items on your hard disk to make programs run faster.”
5. Burn slower: If you’re experiencing trouble, try recording at a slower speed. This will also empty the buffer at a slower rate, and could solve the problem. This is especially important when copying many small files. It’s also helpful when copying from a CD-ROM drive that runs slower than the burner drive.
6. Test first: While CD-R discs are relatively inexpensive, other media formats, like DVD-RW discs, can be expensive. So before burning, have the software do a test burn. Then, while doing a large run, test occasionally to make sure you’re getting good copies.

We all know that awful feeling of ruining perfectly good blank CD or DVD media, but if you follow these simple steps (and with a little luck), you can avoid disc burn errors as much as possible.