Data protection: recovery with tape

Computer Technology Review, Oct, 2004 by Rich Harada

In all data protection and business continuance infrastructures (whether for backup, disaster recovery, archiving, or any other data storage protection), tape storage can be used to handle the restoration of the original data when something goes wrong. All data protection and business continuance (DP/BC) systems should be designed with data recovery as the primary goal. The method used to protect the data, such as critical tape backup, is a means to meeting the requirements for data recovery.

In a small office or home office (SOHO) environment, it may be feasible to have a single data protection approach, or a standalone tape drive, to store all data, applications and operating systems that are used to operate the business. But in larger organizations, where there are different departments, locations, and processes, a "one-size-fits-all" approach may be more difficult to achieve. Different methods may be needed to cover the different types of digital information, such as database records, applications, messages, and other office files.

For example: A disk image taken from a "new" desktop can be used to recover the operating system, configuration, and basic applications to the same desktop's replacement hard disk or to another computer; but a computer that had user-created data or added programs may be best stored on a tape back-up so recovery of the user-specific data along with the system files can be restored.

Additionally, protecting the data on different types of storage repositories (such as mainframes, servers, networked storage, desktops and laptops) may need to be separately addressed but centrally coordinated. Variables to consider when developing a DP/BC system would include the amount of data to be protected, the window of system availability, and the criticality of the data.

Value Proposition

Business objectives, such as the amount of downtime or the amount of lost data that the business can successfully withstand in the face of a disaster, should be the driving forces behind a DP/BC program. Since these protection programs act as your computer's insurance policies and only provide value when bad things happen, it is also a key business objective to balance the costs of these systems with the value of the data that needs protecting.

Start With the Basics

The foundation for almost every DP/BC program is the use of tape to store copies of important and critical information, both locally and in remote locations, to provide recovery options whenever data is lost due to any reason. Tape protects data from almost any threat or event, and provides reliable storage at high capacities, with fast data transfer speeds at the lowest available cost. Of the many storage components in your data center, tape storage should be part of the total solution, no matter what the specific requirements are for data availability.

"Any backup or disaster recovery system that does not incorporate tape is either not providing total data protection or is costing the organization more than it needs to spend to protect many of its assets," says Dawn Wortman, Fujifilm's Data Tape Group marketing manager. "Tape provides great value while meeting the protection requirements for the majority of most companies' data assets."

Not All Data is Created Equal

Each type of data is not of equal value to the organization. Not only is the value of data attributed to its application, but also to the number of people who need to have access to it. While you do not want to spend more on a total DP/BC solution than the financial losses you might reasonably expect without one, the only way to achieve this is to tailor specific layers of protection to each data asset class. Spend as little as possible at each layer, assigning only those applications and data classes to the more expensive protection systems as they are truly needed.

Some data sets, such as those found in transactional databases, need to be available all of the time. An inability to access an inventory list or customer account information can have an immediate and detrimental impact on a business' bottom line by shutting down the order processing flow. In an e-business, the customer will likely go to a competitor if an order cannot be placed at that moment. In contrast, losing a document, an e-mail, a spreadsheet, or even a product design diagram may cause work to have to be redone, but the impact may be less dramatic and less time sensitive, nonetheless important.

For each application, and for each data set that it generates, the storage administrator should determine two main business-related requirements:

Recovery Point Objective (RPO): How much data, measured in time from the point of failure going backwards, can afford to be lost and/or recreated? In other words, how often does the data need to be copied to the DP/BC system? In a standard backup regimen, the RPO might be 24 hours--the maximum time since the last backup was performed.

Recovery Time Objective (RTO): This measure relates to how long the organization can afford to be without the information. Does the business start losing money the second this data becomes unavailable, or after a few hours, or after a few days? Again, it's critical to balance the cost of the solution against the value of the data.