Reliably reading bar code labels on tapes

One of the most frustrating things that can happen in a backup operation (or worse yet, during a restore) is for the tape library to fail to read the bar code label identifying a tape cartridge. The result can be anything from a lot of manual fiddling to a discarded tape cartridge. In general, the best thing to do is to discard a cartridge the first time the drive or library fails to read it -- after recovering the information on the tape, if necessary. Fortunately there are a number of steps you can take to prevent problems.

Modern tape drives and libraries are remarkable finicky about the labels. If the there is not a clear, high-contrast distinction between the white and black bars in the bar code, the device may read the label erratically, or more likely fail to read it at all. This can be true even if another device of the same make and model can successfully read the label. The relevant ANSI specification, X3.182, lays out in considerable detail how a bar code must appear to the reader. It also establishes quality levels for bar codes. In general backup tape equipment expects labels meeting the highest, grade A, quality standard.

The reason this causes so much trouble in data centers is that the typical computer printer cannot consistently produce labels of this quality and trying to do so give inconsistent results. Hewlett Packard, along with many other makers of tape drives and cartridges, recommends using pre- printed labels from approved suppliers as a

Requires Free Membership to View

way to avoid trouble.

Print quality aside, HP says there are other things which can cause problems with cartridge labels. For example some libraries have problems with DLT cartridges with more than 7 characters because of the density of bars and spaces. Likewise, HP says, some libraries have trouble with LTO tape labels containing more or less than 8 characters. Another problem with LTO labels, according to HP, is that HP LTO libraries expect two lines of bar code instead of the HP-specified dual line bar code.

HP discusses labeling issues in a white paper titled "HP Bar Code Label Requirements, Compatibility and Use" available at: http://www.hp.com/products1/storage/products/storagemedia/WP_barcode.pdf

For more information:

TIP: Be careful with tape labels

Related links: Automated tape libraries

Related links: Backup/Archive

About the author: 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.

This was first published in January 2004

There are Comments. Add yours.

TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to:

Disclaimer: Our Tips Exchange is a forum for you to share technical advice and expertise with your peers and to learn from other enterprise IT professionals. TechTarget provides the infrastructure to facilitate this sharing of information. However, we cannot guarantee the accuracy or validity of the material submitted. You agree that your use of the Ask The Expert services and your reliance on any questions, answers, information or other materials received through this Web site is at your own risk.