Do you really need a SAN?


Most IT organizations today struggle with high costs and complexity related to their enterprise storage needs. While the industry dogma for the past several years has pointed to use of a SAN for best application performance, data protection, and consistency of management, the experience of most organizations has been less than satisfactory.

Now, a number of application vendors are proposing to take on more storage management tasks within their code base, aiming at delivering simpler, cheaper storage. While applications have a lot of ground to cover to gain parity with products offered by dedi- cated storage vendors, there are significant potential benefits if they get it right.

The problem

A combination of technology inflexibility and organizational dysfunction has led most enterprise storage systems down a path of inefficiency. SAN-based storage was supposed to deliver:

  • Reduced hardware acquisition costs through increased utilization;
  • Less complexity through consistent management;
  • Better performance through increased aggregate spindle count;
  • Improved data protection through array-based replication and backups.

Unfortunately, the reality is that many of these goals have not been accomplished. Forrester Research interacts with hundreds of enterprises every year, and the vast majority of these organizations have little good to say about their storage environments. Firms consistently identify storage as among the costliest and most complex areas of IT service delivery, and cite the following problems as specific woes:

  • Low aggregate utilization leads to high cost of infrastructure;
  • Limited workload-sharing creates islands of stranded storage capacity;
  • Vendor heterogeneity limits compatibility of infrastructure components;
  • Block storage devices have limited context of information, hindering tiering and archiving initiatives.

Application-centric storage is emerging as a possible alternative. Managing storage directly within the application could break down some of the organizational barriers that limit efficiency. Storage experts who report to application teams would be better in tune with forecasting growth and could streamline the provisioning process. Managing to defined SLAs would be easier as well if the infrastructure and application staff were more closely aligned.

Applications are likely to have better success with tiering and archiving since they have more context about the value of information at any given time than do block storage systems. Configuration could become less complex since the hardware and software would be more tightly coupled, placing less reliance on architecture experts.

Finally, there is a potential for application software to manage cheaper hardware composed of industry-standard components, compared to custom ASIC-based storage hardware that is far more expensive.

Instead of striving in vain for a consistent pool of efficient storage resources, building silos around applications that have the native ability to manage the resources themselves could be a viable option, and key application vendors are moving in this direction. Some of the emerging options:

  • Oracle offers branded storage hardware under the Exadata label. Using its Automatic Storage Management (ASM) feature to control the flow of data between application servers, and storage servers provided by technology partner HP, the Exadata system is a hybrid of software and industry-standard hardware that Oracle will sell directly.
  • Microsoft recommends DAS for Exchange 2007. Exchange has long had a best practice for configuration that precluded adding other workloads to the storage array it runs on, which has served to put it on an island. Now, with the addition of Cluster Continuous Replication (CCR), the application can manage its own high availability and replication.
  • VMware offers native storage management capabilities. The virtualization market leader continues to add storage features to its application stack. For example, VMFS offers volume management capabilities within virtual machine management, and VMware’s recently announced vStorage includes native thin provisioning and other key storage features. While many of the storage features within VMware leverage SAN array capabilities, the control and management is substantially shifted to the application realm.

Painful change?

Clearly, the concept of application-managed storage represents a significant shift from current understanding of maximum efficiency and capability in the enterprise, and a move to such a model would not be without pain. Enterprise storage changes very slowly, with new archi-tectures having to fit refresh cycles to avoid disruptive and costly forklift upgrades. IT purchasers are notoriously conservative, so significant momentum will need to be present before a majority will move in this direction.

Most significantly, the capabilities of the applications will need to continue to improve, because such a shift cannot happen at the expense of application performance or data availability. In the current economic times, it will be incumbent on both pure storage vendors—and application vendors that may unseat them—that their solutions are the most effective choice, both operationally and economically.

Time will tell whether this becomes a true sea change in the enterprise, or if it is just a minor blip in the current evolution of enterprise storage.


ANDREW REICHMAN is a senior analyst at Forrester Research. To receive free related research from Forrester, visit: www.forrester.com/sanarticle

This article was originally published on March 01, 2009