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Issue of August 2004 

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Managing storage through layers

A look at how Storage Area Management or consolidation of storage resources is a solution for most storage management challenges. by V. Vivekanand

It is apparent that information storage is regarded highly in enterprises, as it has turned out to be a very potent tool for remaining competitive in today's dynamic business environment. This has led to a tremendous explosion in demand for storage infrastructure. While the importance of storage is undeniably growing, enterprises are trying hard to transform storage from being seen as a cost component to that which generates more revenue.

Even though the cost of raw storage is declining by the day, the prevalence of fiber channel technology in the networked storage era has led to a situation wherein the cost of manpower required to administer storage is escalating. And with shrinking IT budgets, storage administrators are finding it increasingly difficult to meet the demands placed upon them as they try to manage the storage infrastructure. This has become a deterrent for enterprises in their efforts towards transforming storage from a cost center to a revenue enabler. Therefore the primary challenge here is to manage the entire storage architecture, which, instead of having a small footprint, has a varied and heterogeneous footprint. This situation puts the performance of business applications, and the business itself at risk.

SAM (Storage Area Management) or consolidation of storage resources has apparently evolved as a viable solution for addressing these challenges. However, not all SAM solutions address the challenges faced by storage administrators.

When considered from a business point of view, SAM is all about quality of service. In a typical organization, storage administrators have to manually manage the various elements of storage infrastructure, which may include file systems that are linked to the database, host bus adopters (HBAs), SAN Fabric switches, the host server, the storage system itself, and the individual disk drive. The entire chain from drive to application has to be linked. This is a labor-intensive, error-prone, and slow process adding, up to delay and higher costs.

However, in today's scenario, businesses that are able to deliver high levels of service easily will automatically reap benefits, whereas businesses that cannot will be in trouble. For instance, when an application experiences unexpected activity, it may not have the storage service that meets its requirement. Consequently, performance and service deteriorates leading to crashes and downtimes.

Layered model

While the implementation of a SAM practice seems the most obvious solution in such a scenario, it is important for administrators to recognize change and revisit the storage setup. This is because, if they have to effect change, it has to be done not in months but in a matter of hours. They need to understand that the implementation of SAM should enable them to manage the complex SAN infrastructures, storage resource management to address process issues, and storage provisioning to enable new applications to come online quickly. In this manner the SAM solution is able to deliver significant TCO improvements and faster ROI.

However, in order to get the most out of a SAM implementation, it is important to follow a layered model for storage management; the whole industry is slowly moving towards this. This type of model relies on building layers within the storage infrastructure and it is based on the industry-wide standards initiative called CIM (Common Information Model). This model enables management systems to recognize and exchange information in a heterogeneous storage environment that houses different solutions from various vendors.

CIM offers a powerful foundation for cross-platform SAM implementation. Though the industry has not reached a consensus on the exact definition of the layers, one model, which has identified four basic management layers, is slowly gaining prominence. The four layers comprise of reporting, path management, event monitoring and automation control and they are addressed in succession.

However all these four levels strongly depend upon the base level, the discovery level, which serves as the building block for this model to work. At the outset organizations need to understand what storage resources they have and where it is. This is a very cumbersome process, which earlier used to comprise of reams of spreadsheets, whiteboards and handwritten notes.

A holistic approach

Ideally a good SAM solution should help administrators get a holistic perspective of all the elements involved in a storage infrastructure right from the LUN (Logical Unit Number) all the way to the application. And this has to be viewed from the application's viewpoint. This helps administrators to discover, track and locate the existing resources and new resources that are being added into the storage infrastructure. This apparently provides a very logical platform that can be used to manage storage in a situation wherein enterprises prefer to build storage infrastructure by sourcing from different vendors.

Once the storage administrator discovers all the elements within the storage system, it is important for them to understand how the resources are being used. This is because, in order that all mission critical applications are functional, enterprises often resort to having buffer storage to meet unforeseen circumstances. However, automated reporting and monitoring to determine what additional resources are needed, and when they are required, comes out as a preferable approach. From this viewpoint, the SAM solution should be able to optimize the existing storage resources rather than rely on buffer storage capacity to keep the applications up and running.

Hence, ideally, while addressing the reporting level in storage management, the SAM solution should be able to provide an elementary overview across the entire storage infrastructure, so that they can continuously monitor storage from LUN to the application. Further, complementing the comprehensive reporting and monitoring functionality, the SAM solution should be able to provide administrators with predictive management tools based on historic data so that outages can be anticipated even before they happen, and corrective actions can be taken. With such a reporting and monitoring system in place, administrators can optimize the usage of existing resources, and they can balance loads and shift excess capacity from one server and application to another. This eliminates the need for excess and "unnecessary" capacity, while existing "excess" capacity and bandwidth are available elsewhere within the existing infrastructure.

The next level after the reporting layer has been addressed, is that of path management. As emphasized earlier, the key to SAM is quality of service, and this is ensured through good path management. This is because, one of the key aspects of path management is to monitor the flow of data, from the storage resource to the application, so as to ensure that the application is receiving the required levels of service to perform optimally. Besides this, the path management function also entails provisioning of storage resources depending on the nature of the requirement. However, it is important to understand that this cannot happen unless the first two layers of discovery and reporting are in place.

When administrators have all the necessary data—that helps them understand the storage resources, the ways to optimize storage, and the flow of data that is required to maintain different levels of service that different applications demand—they no longer need to struggle to understand the different fault and problem alerts that come their way. The data helps them exercise greater control and initiate proactive measures to correct problems that come their way. This is the third layer in the storage environment wherein the SAM solution helps administrators troubleshoot problems easily and isolate components that need correction. This is enabled by the data flow alerts that the SAM solution sends to them periodically in relation to the applications' service level requirements.

With the three layers in place the last functionality the SAM solution should offer is to automate the entire management process using a policy-based management engine. For instance, when a critical application approaches a threshold signaling that the application will soon run short of storage space, the system acts automatically and allocates additional storage to that application. By intelligently taking over an administrator's function, it allows the administrator to be free of routine tasks so that he can focus on more strategic issues. At this level organizations can fully leverage on the SAM implementation to improve storage service quality while reducing costs.

While addressing these layers for management of storage, it is important to bind together these layers and populate them with the various specialized management tools coming from different vendors. Therefore, ideally the SAM solution should be one that leverages on the synergies of an open, management framework and powerful intelligent storage systems. This requires a collaborative approach that can be achieved by developing strategic alliances to deliver SAM solutions that fit more into multi - vendor storage environments and are based on broad integration with third-party Storage Area Management software.

The writer is Sales Director, S AM Solutions, APIA, Hitachi Data Systems

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