The Essential Guide to Disaster Recovery

High Availability / Disaster Recovery
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Employ effective strategies for timely data protection and recovery.


Editor's Note: This article is a distillation of the free white paper "The One Essential Guide to Disaster Recovery: How to Ensure IT and Business Continuity on i5/OS and AIX" available at the MC Press White Paper Center.


System downtime and data loss pose intolerable risks to every business. From IT departments to the boardroom, managers have seen the importance of business uptime and data protection to continued success, productivity, and profitability. This article provides effective strategies and technologies to protect data and provide fast recovery should data be lost or corrupted due to accidental or malicious action.


Planning for recovery--designing and implementing a solution to reduce the amount of recovery time needed after an interruption--is a pressing requirement for businesses of all sizes. When implementing an operational plan that ensures quick data and applications recovery, IT managers need to ask themselves the following questions:


• Are my applications and data recoverable without impacting business operations?

• Do the data protection strategies currently available meet my recovery point and recovery time objectives?

• Can I afford to implement a comprehensive plan that covers both local and remote (disaster) recovery requirements?

• Are there cost-effective alternatives that meet my requirements?


Bottom line: Businesses face a variety of risks to their data, such as accidentally deleted files, data corruption from viruses or hacker attacks, software/hardware failures, power outages, or a wide range of natural disasters. Business and IT managers need a data protection and recovery strategy that keeps their organizations running.

Tape Backups: First Line of Defense

For most businesses, some form of data protection already exists--most likely a tape-based backup. Periodically, someone shuts applications down to perform a backup to tape. Depending on the volume of data that is being copied, this may take several hours and requires manual intervention to set up the backup job, run it, confirm that it occurred, and then return the application to operation.


The backup copy may be kept locally in case data needs to be recovered in the near term, and eventually it may be moved to an offsite location for archival storage purposes. The reason to make and keep copies of your data is so that, in the event of some sort of event or catastrophe that deletes or destroys data, you have a clean copy safely tucked away to use for recovery purposes.


Tape is used for backup and archive because it is very inexpensive, but it is an old technology that has been available almost since the dawn of computing. There are several issues with tape-based backup:


• Tape-based backup is a time-intensive process that is potentially disruptive to your applications; this issue is commonly referred to as the "backup window" problem.

• Because of its impact on applications and resources, tape-based backups are usually not performed more than once a day and often only once every several days, meaning that there are very few tape-based recovery points available for use over the course of a week.

• Because data changes very frequently (sometimes within seconds or minutes), fewer recovery points mean risking the loss of large amounts of current data for a given recovery.

• Once it is clear a recovery needs to occur, it takes time to perform recovery tasks: locating the correct tape, transporting it (if offsite), restoring it to disk, and restarting the application with the recovered data.

• As a storage media for backup, tape is not entirely reliable. In fact, leading analyst groups--such as the Gartner Group, Enterprise Strategy Group, and Taneja Group--state that as many as one in four backup tapes suffers from some sort of problem that precludes performing a recovery.


Transporting tapes to offsite facilities for archival purposes also has inherent risks. Several highly publicized tape losses during physical transport (by truck) hit large companies like Bank of America, Citigroup Inc., ChoicePoint Inc., and LexisNexis in the United States and resulted in the loss of hundreds of thousands of company records.


Replication of data across secure IP-based networks is a much faster, easier, and safer way to transport data to offsite locations for archival storage purposes. If an organization is driven by either business or regulatory requirements to deploy a disaster recovery solution, a pure tape-based strategy can pose undue risks.


Tape-only backups are no longer a feasible data protection strategy in business environments that require frequent access and updates to critical business data. The two most important metrics for determining the optimal capabilities of any data protection strategy are the recovery time objective (RTO) and the recovery point objective (RPO).


Recovery Time Objective (RTO) defines how quickly data and applications need to be restored and have them fully functional again. The faster the RTO requirement, the closer a company moves to zero interruption in uptime and the highest level of data protection.


Recovery Point Objective (RPO) defines the point at which the business absolutely cannot afford to lose data. It points to a place in each data stream where information must be available to put the data back in operation. Again, the closer a business comes to zero data loss and real-time access, the more continuous protection of data will be required.

Matching Business Needs to Data Protection and Recovery

What is the best method to meet the data recovery requirements of each system in an organization and achieve the optimum and appropriate RTO and RPO? Some organizations, or some particularly critical information within an organization, might require an exceptionally fast level of recoverability.


It is possible that different RTOs and RPOs exist for various types of business-critical information. For example, a supply chain application that feeds a production plant may require a recovery time of only a few minutes with very minimal data loss. A payroll system updated weekly with only a few records might only require a recovery time of 12 hours and a recovery point of 24 hours or more before the impact will affect the business. Any data protection strategy must ensure information remains as accessible and available as needed to continue to drive revenue, profitability, and productivity at acceptable levels no matter what planned or unplanned events occur. The data protection solution should:


• Protect data to a level that meets business requirements and RTO and RPOs.

• Manage business uptime as automatically as possible to streamline operations and save time.

• Assure the integrity and quality of data during interruptions and when it returns to full operations.

Continuous Data Protection (CDP): A Breakthrough Innovation

The goods news for businesses is that the technology for data protection is easier and more effective than ever. Innovations have kept pace with the need to provide comprehensive data protection and make data recovery a quick and easy process. Perhaps the most exciting recent innovation in this area is continuous data protection, or CDP.


CDP is a flexible disk-based technology that enables businesses to quickly and easily recover data to any point in time. For example, it is not uncommon for a user to accidentally delete a critical file. Or for a virus to corrupt business data. These actions render the data unusable, even though the server or other hardware resources continue to work as expected. CDP enables businesses to recover a version of their data to a point in time just prior to the accidental deletion or virus corruption. This earlier version of the data can then be restored to the production environment.


Unlike tape backups, CDP technology does not require the interruption of applications to perform backups. It works continuously to back up critical data to an alternate server so it can immediately be recovered from any point in time. If an important document is deleted or data corruption occurs due to a virus or hacker attack, CDP dials back to the point in time just before the problem occurred. Recovery occurs immediately with just the push of a button. Recovery for much larger amounts of data takes only minutes. With CDP, data protection and data recovery occur with only a fraction of the time and labor resources required by a tape-only strategy. It also eliminates the threat of major data loss posed by the infrequent recovery points of a tape-only strategy.


Continuous Data Protection incorporates several techniques from traditional backup, replication, and snapshot solutions. How the CDP solution achieves its goals has much to do with its architecture and configuration. It is important to note the difference between "True CDP" and "Near CDP" solutions when evaluating a data protection strategy:


True CDP captures every data write and transfers them to a secondary disk. True CDP enables a data "undo" by allowing recovery to any point in time. This is especially beneficial for a data corruption issue, such as a virus. With True CDP, it is easy to identify a tainted email, for example, and then roll back to a point just prior to the time the email was received.


Near CDP differs from True CDP in that data can be recovered only to specific points in time. For example, Near CDP will copy data when a file is saved or closed, so the recovery point is only to the last known saved file. In some cases, this could be several hours or more. In high-transaction environments or environments with rigid compliance or governance regulations, this may be insufficient. The efficiencies and flexibility of CDP translate into much superior data protection and recovery, as well as cost savings realized through the elimination of both planned downtime for backups and lengthy, error-prone tape recovery processes.

The Next Step in Data Protection

For businesses looking to take the next step in their data protection strategies, CDP is an essential consideration. Most IT analysts agree businesses will incorporate this strategy in the next few years as part of an integrated solution. CDP enables organizations to reverse data corruption in a fraction of the time and labor required for recovery from tape. It does not require planned downtime for backups and recovers data instantly at the push of a button. Whether installed as a standalone solution or integrated into a high availability solution, CDP provides the easiest and most effective protection against the loss of critical business data.


To download the free white paper "The One Essential Guide to Disaster Recovery: How to Ensure IT and Business Continuity on i5/OS and AIX," go to the MC Press White Paper Center. For further information about Vision Solutions, visit or call 801.541.7769.