Considering Deduplication for a Midrange Data Center? Seven Questions You Should Ask - Page 2

By Steve Mackey | Posted Aug 23, 2010
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5. What is the easiest way to implement deduplication?

The choice facing most IT departments is between deploying deduplication appliances or carrying out deduplication within the backup software. There is no universal answer about which approach will be easiest to deploy. There are some guidelines, however. 

With appliances, currently the most wide-spread approach to deduplication, the backup data is all sent to the device and deduplication occurs at the target. With appliances, users can add systems in place of, or along side of, existing backup targets and make very little change in the overall backup methodology. Because the deduplication is carried out on a purpose-built appliance, it never increases the load on backup clients or media servers, and it makes the deployment of operations like replication straightforward. As the most common method, it is also the most mature—which usually means faster deployment and fewer service needs.

With a software approach, the backup application adds deduplication to the other tasks that it carries out, either on backup clients or on media servers. By deduplicating data before it is sent to a target, less data has to be transmitted over the network—the idea is similar to performing compression in software, and in fact deduplication processes almost always include compression as well. Since deduplication is a relatively high overhead operation, there's a chance that backup operations may slow down so deployment may require adding new servers or dedicated storage. This tends to increase the cost and complexity of integration.

Either approach can make sense depending on specific circumstances. To decide what is best for you, think about where bottlenecks are in your system today, whether or not your current media servers are underutilised, and what level of integration effort makes sense for your specific situation.

6. Should I eliminate my tape storage altogether?

Although most end users who adopt deduplication reduce their use of removable media, very few eliminate it entirely—and for good reason. Typically, users have roughly three tiers of needs for backup: daily backup and restore, near-term DR protection, and long-term data retention. It makes sense to look at different technologies for each tier and to talk to vendors who understand them.

Daily backup and restore: Many users find that disk read and write profiles give them advantages for day-to-day backup and restore. Deduplication adds the advantage of letting them store data on disk longer so that more restores can take advantage of those profiles.

Near term DR: Replication enabled by deduplication lets users with multiple sites replace removable media with remote replication for DR. As a result, they see more restore points, reduce costs, and automate what is for many a very manual operation.

Long- term retention: Removable media continues to provide strong economic and security value. Tape consumes the least power, space, and cooling of any storage, making it the preferred medium for long-term retention. New technologies for tape, including encryption and media integrity analysis, have made it more secure and reliable.  

7. Where can I get objective advice?

There are lots of ways to get objective advice about which approaches match best to your specific needs. Some independent analysts who spend time talking directly with end users provide very useful and objective information about others' experience. But if you aren't a client of the big-name analysts, there are other options. 

One of the best is an experienced reseller. Good resellers, who have a track record of helping IT departments deploy technology, understand the reality of what will work for specific environments and they have a vested interest in helping you succeed. 

You can also talk directly to vendors. If they offer multiple technologies, they are likely to provide a broader view than if they offer only one product. And if you have a vendor that you already trust for backup, it makes sense to see what kind of deduplication options they have.


Quantum is exhibiting at 360�IT, the IT Infrastructure Event held 22nd – 23rd September 2010, at Earl's Court, London. The event provides an essential road map of technologies for the management and development of a flexible, secure and dynamic IT infrastructure. For further information please visit

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