Addressing the challenges of data protection; key data must be 100% reliable, accessible and up-to-date - Backup/Restore

Computer Technology Review,  Jan, 2004  by Mehran Hadipour

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Data loss, whether due to human or equipment error, or due to natural or artificial disaster, has business implications of enormous proportions. The need for key data to be 100% reliable, always accessible and fully up-to-date is clear for a growing number of enterprises. These conditions must be met at a cost that is affordable and without in any way hampering the operation of critical business applications.

Companies need to protect mission-critical data from unplanned events, such as a power outage, natural disasters, etc., which could interrupt business operations. Without an adequate disaster recovery solution in place, lost data and prolonged downtime could result in a loss of massive amounts of revenue and productivity, as well as customer trust and brand equity, which take years to build but just hours to destroy. With hourly downtime costs over $6M for some organizations (Gartner Study), the need for an effective disaster recovery solution is high-up on the strategic agendas of the CIOs of leading international companies.

Data drives much of the value created by the enterprises today and there are a number of reasons why enterprises worry about data protection in event of a disaster. Loss of critical data could have consequences such as:

* Bankruptcy

* Loss of revenue

* Loss in productivity

* Loss of customers

* Decreased customer loyalty

* Non-compliance of regulatory requirements

* Legal implications

* Missing key audit requirements

* Loss of competitive advantage

* Bad public image

Data Protection Challenges

Protecting high-value data and delivering 24x7 data protection and business continuity is of paramount importance to organizations throughout the world. Unfortunately, those organizations that have embarked on this mission have found considerable challenges along the way: from the many infrastructure challenges associated with managing heterogeneous platforms, applications and data, to the challenges presented by the limiting and costly technology options available today.

Infrastructure Challenges

IT infrastructures usually include a myriad of server, storage, and application platforms. In addition, data and applications often span across distributed or clustered servers and storage. Supporting and protecting these heterogeneous platforms is a complex issue. Furthermore, as not all data is of equal value to an organization, and as the value of data can change, determining how to most effectively protect this data is an ongoing problem.

Managing an end-to-end DR solution across an enterprise is currently an extremely complex challenge. Different storage platforms offer proprietary DR solutions, each with its own management challenges. Host-based solutions can impact server performance and require another layer of data management. In addition, many DR solutions today also require additional infrastructure (like protocol converters) that in turn add yet another layer of complexity. And of course, organizations must deliver DR solutions without impacting the performance of key applications.

These many infrastructure challenges result in costly implementations that often do not address the complete DR needs of an organization.

Data Replication Challenges

Enterprises need a disaster recovery solution that delivers a reliable up-to-date remote copy of its mission critical data but will not result in performance degradation of the applications; it must be cost-effective and therefore must use minimal extra storage (an original and one copy should be enough), and must support the organization's specific (and dynamic) availability requirements.

Data replication methods, from synchronous to asynchronous to point in time, have evolved over the years, in an attempt to address these dynamic needs of enterprises. Unfortunately, whereas each method offers advantages over the others, significant disadvantages are also present in all.

Synchronous replication addresses the very fundamental requirement for any effective disaster recovery solution of having an up-to-date remote copy of the data. With this replication method, every write transaction must be acknowledged from the remote site. This method ensures that an up to date copy of the primary site is maintained at a secondary site and that if a disaster occurs in the primary site, the secondary site will be consistent with the primary site. This works well for replication within a local SAN environment; however, extending this approach to transfer data over the WAN results in significant latency problems, high bandwidth costs and a dramatic degradation in the performance of critical business applications. This can have a highly disruptive effect on business operations.

[FIGURE 1 OMITTED]

With asynchronous replication every write transaction is acknowledged locally and then added to a queue of writes waiting to be sent to the remote site. Although asynchronous replication does not reduce the bandwidth requirements associated with synchronous replication, it does reduce the latency problems. Unfortunately, however, for "write intensive" applications performance will eventually deteriorate to that of synchronous replication.