Tip

Decide if you need speed, or sophistication

The fastest way to do a backup is to back up the physical storage devices without regard to logical structure of the files, the nature of the application being backed up or much of anything else. This involves streaming data off the device and onto the backup device at the maximum throughput the system can produce. Often a raw device backup can offer speeds several times those possible with more structured backup approaches.

Because of its sheer speed, raw device backup seems attractive to organizations with a lot of data and short backup windows. While it is a useful technique, this kind of backup has some serious drawbacks that become important when you actually need to use the backups.

The biggest problem is the lack of structure in raw device backups. Not only do they ignore the file structure on the disk, raw device backups usually can't distinguish used and unused sectors. Everything gets backed up, whether there is data there or not.

Another consideration is that a raw device backup requires that the system be inactive while the backup is being run. A straight disk-to-tape data dump has no way of handling activity while the backup going on.

Nor does a raw device backup necessarily make the best use of limited backup windows. If the size of the window varies regularly, as in the case of an organization with less activity -- and hence a wider backup window -- on the weekends, it may be more efficient to do incremental backups during the

Requires Free Membership to View

week and a full backup on the weekends.

Sun Microsystems discusses raw device backups in the context of high-end backup in a white paper titled "High-Speed Database Backup on Sun Systems".


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 August 2002

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.