Posey's Tips & Tricks

Why You Need Separate Backup and Archiving Strategies

Let's explore the financial and operational benefits of differentiating backup and archival strategies in data management.

Backups and data archives have a lot in common with one another. After all, both are geared toward data preservation. In some cases, backups may even be used as a substitute for a dedicated archive solution. I have seen organizations make special monthly or end-of-year backups purely for the sake of long-term data retention.

Before I tell you why I recommend having separate backup and archive strategies, let me just say up front that every organization's needs are different. If your organization doesn't currently handle archiving separately from data backups, but what you are doing works really well for you, then you should probably keep doing whatever it is that you are doing.

The main reason why it makes sense to separate out backup and archival storage is cost. Most cloud storage providers (though there are exceptions) treat backup storage as hot storage and treat archival storage as cold storage. From a practical standpoint, this means that backup is readily accessible at any time, whereas a provider might need a few hours (or even a few days) to mount the data that is stored in your archives. Of course, backup storage generally has a much higher cost per gigabyte than archive storage does.

If an organization does not have all that much data, it may be tempting to just store both backup and archive data in a hot storage tier. It may be worth the extra cost just to have easy access to archive data. One thing to keep in mind is that the total cost of using backup storage may be several multiples of the stated price.

The reason for this is simple. One of the primary principles that has guided data protection for generations is something called the 3-2-1 rule. Admittedly, the 3-2-1 rule is a bit dated and there are several modern iterations that work a bit differently. Even so, one of the main principles that is engrained in the 3-2-1 rule and all of its modern variants is redundancy. In other words, your data can never be considered to be fully protected unless several independent copies exist. Of course, there are costs associated with each backup copy that you maintain. In other words, the larger the backup set, the higher the storage costs, particularly if you have multiple replicas set up.

Redundancy may also exist for archive storage, but that cost tends to be much lower simply because all copies reside on cold storage. Some organizations also use data lifecycle management techniques to further reduce the cost of archive storage by automatically purging data once it reaches a certain age.

Another thing to consider is that backups and archives serve totally different purposes. Think about the systems that you back up every single day. Would there ever be a reason to restore a backup that is six weeks old? Probably not (though again, exceptions do exist). As such, it probably doesn't make any sense to store weeks' worth of backup recovery points. Instead, it's usually a good idea to focus on reducing the size and complexity of your backups based on your operational and regulatory requirements.

Being that modern backup software often relies on changed block tracking, it may seem that reducing the number of recovery points that are retained would do almost nothing with regard to shrinking your backups because you are ultimately storing the same number of blocks. However, if you are also using a data lifecycle management policy to move aging data to your archives, then blocks will be removed from your primary storage. Having a shorter backup retention period means that the blocks associated with the now archived data will be released from your backups more quickly, thereby helping to shrink your backups and reduce your costs.

One more benefit to this approach is that shrinking your backups may also help you to be able to complete a restoration more quickly. This doesn't hold true in every situation. But if, for example, you were attempting a restore an entire volume, having a smaller backup would generally mean a faster restore job.

About the Author

Brien Posey is a 22-time Microsoft MVP with decades of IT experience. As a freelance writer, Posey has written thousands of articles and contributed to several dozen books on a wide variety of IT topics. Prior to going freelance, Posey was a CIO for a national chain of hospitals and health care facilities. He has also served as a network administrator for some of the country's largest insurance companies and for the Department of Defense at Fort Knox. In addition to his continued work in IT, Posey has spent the last several years actively training as a commercial scientist-astronaut candidate in preparation to fly on a mission to study polar mesospheric clouds from space. You can follow his spaceflight training on his Web site.


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