Advancing Storage Management via SMI-S and Management Frameworks
By Mark A. Carlson, Senior Architect at Sun Microsystem's Storage Group;
co-chair of the SNIA's Management Frameworks Technical Work Group

Storage management solutions have evolved greatly in recent years. While the Storage Management Initiative Specification (SMI-S) has delivered a breakthrough in standards-based management, we continue to see new opportunities for improvement. There are additional options for progress, especially in accelerating the time to market for new technologies. In this article, we'll take a look at the evolution of storage management and what the next phase will bring.

In the past, storage management was executed via individual vendor management tools or enterprise management applications. In this less than ideal environment, multiple vendor user interfaces led to discontinuity and inconsistency, which often resulted in errors. With each vendor required to create adapters for proprietary Application Programming Interfaces (APIs) (Figure 1), there was no opportunity for automation, which increased the cost and complexity for the end user.

Figure 1

Enter SMI-S
As a result of this need, the industry joined together to create the Storage Management Initiative Specification (SMI-S). Now a certified ISO and ANSI standard for the interoperable management of storage resources, the SNIA's SMI-S builds on the Common Information Model (CIM) to specify a common interface between storage devices and management applications. SMI-S consolidates the management function and reduces the complexity of managing devices (Figure 2).

Figure 2

By providing a basic information model for instrumentation of the storage resources, and by delivering a set of standard protocols for the transport of that information model, SMI-S has enabled interoperable storage management. These new capabilities have resulted in greater productivity for storage management vendors by freeing the engineers formerly tasked with maintaining one-off device adapters to now create more functionally rich management applications. As a result, in addition to the interoperability benefits, end users profit from the increased innovations the standards-based approach facilitates.

Flexible, portable and non-proprietary, SMI-S can be embedded directly into new devices, or can be used through "proxy" to manage new and legacy devices. The incorporation of SMI-S into products gives users more flexibility when choosing their devices and management applications to solve storage management problems.

The power of SMI-S comes from its object-oriented API for managing storage devices. The standard foundation of the API, which is common across all SMI-S implementations, is built upon by vendors via extensions, which allow for added value and proprietary properties without the need to swap APIs. In addition, these APIs can be exposed as a service on the network.

For enhanced interoperability and ease of use SMI-S features multiple profiles, which each address a particular resource domain. Profiles document the equivalent of an API to each type of device/resource, and specifies how to manipulate the Information Model of the device/resource. Each SMI-S profile acts like a service (or set of services) on the network, available to storage management clients. This enables the end-to-end provisioning of storage as a service on the network and allows other network-based services to be created which use that service.

With these and other benefits, SMI-S delivers the basis for interoperability and vendor independence in critical storage management functions.

The New Opportunity
To date, SMI-S has been widely adopted as a storage resource management standard. It laid the foundation for management software to be  written to one set of interfaces, defined by an SMI-S profile, for each type of device.

The next opportunity is to address the fact that there is a delay in the time to market of new standard features, as the SMI-S standard progresses. There is a recognized need to accelerate the delivery, making implementations available to end users more quickly. In addition, there is an opportunity to further free vendors from focusing on infrastructure, so they can concentrate on providing software that delivers new functionality and added value for end users.

To address these requirements, the SNIA is developing a standards-based approach to Management Frameworks, defining the services and service interfaces necessary to provide the core functions for storage management applications. The foundational deliverable of this effort is the Management Framework Reference Architecture, a working draft of which is now available for public review in PDF.

Organized in layers (Figure 3), the Management Framework Reference Architecture includes infrastructure, core and domain-specific services, designed to support the enterprise-level services necessary for the management of storage providers and clients, as well as related infrastructure.

Figure 3

• Infrastructure Services - the lowest level of the Management Framework, which includes the services necessary to interact with the managed elements (devices and installed pieces of software). Services in this layer can be used by any other service in the Management Framework, and provide capabilities for the discovery of agents, collecting management data from agents, and subscribing to and receiving asynchronous events. These services may be extended or added to in the future to support new agent protocols and/or to extend the capabilities of the infrastructure layer.
• Core Services - representing the core functionality of the management framework. Services at this layer are not specific to any particular management domain (such as storage) and are largely separated from having to interact with the agent tier by the Infrastructure layer. The Core Services layer includes the services that are fundamental to any management application, and provide an adequate base upon which to build such an application.
• Domain Specific Services - includes services that are specific to management domains. This specification includes definition of Domain Specific services for storage management. These services do not constitute the domain specific application itself, but extend the core services with additional services that are fundamental to a specific management domain.

• Agents - immediately below the Management Framework, and representing the managed elements, are agents. Agents are assumed to be based upon CIM and SMI-S. Agents that extend SMI-S profiles are allowed, per the SMI Specification. Agents not based upon CIM or SMI-S are also allowed, by converting other information models into CIM via the Infrastructure Layer Services.
• Management Applications - consists of storage and storage network management applications, building on the management framework and using the services and data model defined by the management framework specifications.

Management Frameworks and SMI-S
The Management Frameworks standard and SMI-S are being developed separately to simplify implementation, since Management Frameworks will be used primarily by storage management software vendors. Both standards are being managed in tandem, as part of the SNIA's Storage Management Initiative, ensuring that the standards will continue to operate together in a harmonious manner.

The Management Framework's system of common components, exposed as reusable services for use by applications and other management services, are complementary and additive to the existing SMI specification. For example, SMI-S allows for vendor extensions, as long as the extension remains conformant to the relevant SMI-S profile(s). The Management Framework supports this model by providing the means for vendor extensions to be "plugged in" that support the corresponding, properly-formed vendor extension to SMI-S.

In a given implementation, both the Management Frameworks standard and SMI-S can be utilized for the ultimate in functionality and interoperability
(Figure 4).

Figure 4

Conclusion
The Management Framework effort is designed to deliver standard framework interface(s) for use by storage management applications, and to support multi-vendor applications using the common framework. In addition, it enables vendor differentiation by leveraging the framework investment across multiple vendors, supporting applications from multiple partners and integrating support from SMI-S devices. This allows vendors to focus on adding features and value, without the need to concentrate on infrastructure. As a result, end users will gain access to a broader set of functionality from multiple vendors - more quickly - resulting in a lower cost of management.

About the Author
Mark A. Carlson, Senior Architect at Sun Microsystems' Storage Group, has more than 25 years of experience with Networking and Storage development and more than ten year's experience with Java technology. In addition to co-chairing the SNIA's Management Frameworks Technical Work Group, he is a co-chair of the SNIA Policy working group and serves on the SNIA Technical Council.