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Are full backups a thing of the past?

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It might be premature to declare nightly full backups dead, but tools like continuous data protection and snapshots can reduce a company's dependence on full backups without compromising data protection.

I recently helped a Fortune 100 client evaluate continuous data protection (CDP) products and was asked if full nightly backups to tape were still needed given the advent of disk-based technologies like snapshots and CDP. Trying not to sound like a consultant attempting to please everyone, I answered "It depends."

Snapshots and CDP provide excellent ways to recover data from a specific point in time when no known data loss or corruption existed. But it can take a while to discover a file or database error, and snapshots aren't typically kept for a long time. That's why full backups to tape are a vital complement to point-in-time backup tools, and will remain so in any comprehensive data protection strategy. The tricky part is to decide how to mix and match backup methods to best meet recovery time objectives (RTOs) and recovery point objectives (RPOs), and stay within your storage budget.

In the not-so-distant past, we relied on tape backups for operational recovery, disaster recovery (DR) and long-term data retention. The latter two are often treated as discrete functions with separate data copies even though tape may be the target media. Operational

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recovery usually applies to the loss of data in normal production operations. In those cases, we would use onsite or offsite tapes to recover the data to the point of the last successful backup (our RPO).

Many companies still rely on offsite tapes to recover data after a disaster. Despite advances in tape technology, the tremendous increase in data is making tape backup more time-consuming and less likely to meet business requirements for timely access to data should some form of data loss occur. These issues are driving many storage teams to look at evolving or newer technologies such as virtual tape libraries (VTLs), snapshots and CDP. Here's where these newer data protection technologies fit best.

Detectable file deletion/corruption. When data is accidentally deleted, there's usually an immediate realization that an error has occurred. Traditional tape backup can be used as the data protection vehicle for accidental deletions. However, the quantity of data and its impact on RPO and RTO requirements must be considered (see "How to determine appropriate RPOs and RTOs," below).

How to determine appropriate RPOs and RTOs
Identifying business requirements and determining the technology best suited to satisfy those requirements is a proverbial "chicken-and-egg" question: Which came first? Most companies don't have the opportunity to start with a clean slate and collect all of their requirements before selecting and delivering technologies to support various service levels.

One approach is to clearly document the data protection services currently delivered in terms of recovery point objective (RPO) and recovery time objective (RTO) combinations, as well as the unit cost (e.g., $/GB) to deliver each of those services.

This information can then be presented to internal customers to determine if IT is over- or underdelivering based on business requirements. Internal customers should have an understanding of their business impact analysis, which will help them compare the value of their data to the cost of data protection for a given RPO/RTO level.

This process will help to align business requirements with existing IT services, identify the need to modify existing services, or help you decide if you need to develop new IT services to meet specific RPO and RTO requirements.

This was first published in September 2008

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