The need to optimize SAN management

Posted on September 01, 1999

The need to optimize SAN management

"Storage domain management" meets management challenges in today`s heterogeneous storage area networks.

Eric Burgener

The dynamic nature of today`s business environments has significant implications for the design and deployment of information technology (IT) infrastructure. The explosive growth of the Internet and the emergence of e-commerce as a powerful force across all industries makes IT infrastructure decisions that much more critical to the overall success of an organization.

While executive management grapples with adapting the organization to the new business environment, IT is expected evolve the IT infrastructure to meet those goals. In many cases, however, traditional IT architectures and management paradigms do not provide the necessary flexibility.

The traditional "direct-attached" storage architecture lacks the flexibility to provide ubiquitous, high-speed access to data amid rapid, unpredictable change. The escalating costs of the traditional model, and in particular the management costs associated with that model, have led to a low perceived value for return on storage investments. Storage asset utilization is often sub-optimal. Clearly, the traditional storage architecture is not meeting today`s business requirements.

Storage area networking (SAN) architectures, on the other hand, provide the IT flexibility demanded in today`s fast-paced business climate. Driven in large part by the availability of Fibre Channel subsystems and network components, SANs promise high-speed data access and movement, more flexible physical configuration, improved capacity usage, centralized storage management, on-line storage resource reconfiguration, support for heterogeneous environments, and eventually shared data access.

The SAN market is currently in the early stages of adoption, and because of interoperability issues, homogeneous SANs are easier to deploy. The true promise of SANs is the ability to centrally manage storage resources across a variety of heterogeneous platforms. The ability to support heterogeneous SANs is important because it preserves legacy investments and frees users to choose the storage technologies and products that best meet their needs, regardless of vendor.

But heterogeneous SANs are unlikely if management capabilities are located in either the server or the storage devices. An alternative is to place SAN management functionality in a central location that allows equal access to all SAN resources, including servers, fabric components, and storage devices. This management capability layers directly onto the SAN fabric and is referred to as storage domain management.

What is it?

Storage domain management is a centralized and secure management capability that integrates all existing SAN hardware to provide high performance, high availability, and advanced storage management functionality in heterogeneous environments. The purpose of centralized SAN management is to form the core of a robust SAN fabric that can integrate legacy and new equipment, off-load SAN and storage management tasks from the servers and storage resources, and host SAN-based applications that can be leveraged across all SAN components.

In comparison to a general-purpose platform, a dedicated storage domain management platform offers a real-time operating system for faster response time, more efficient I/O path code to minimize message latencies, and an operating system kernel optimized as a "data movement" engine rather than an "application" engine.

As such, this platform also supports kernel-level features not available in a general-purpose operating system, such as reliable, deterministic message delivery. High availability features, such as integrated path fail-over, on-line management, and dynamic reconfiguration are also supported by the core operating system.

This platform delivers benefits to end users (such as high-performance and high-availability data access) and systems administrators (such as on-line management and storage management task simplification).

As the point of central intelligence in the SAN, a storage domain manager must be able to accommodate a significant amount of capacity growth without load-related performance degradation. The ability to cache significant amounts of data in the management platform is crucial in optimizing the SAN configuration for performance improvements in application-specific environments.

For example, if "hot spots," such as file system journals and database table indexes or logs can be cached, this significantly minimizes message path latencies relative to more conventional SAN configurations. Given a sufficient amount of on-board storage, entire databases and file systems can effectively be cached to achieve performance improvements.

One of the key reasons for moving to a SAN is to improve overall data accessibility. If single points of failure exist, many of the potential benefits may not be realized. For this reason, the data itself and the access paths to that data must be highly available at all times. Minimizing downtime due to failures must be addressed through the use of integrated fault management capabilities such as automatic I/O path fail-over, logical hot sparing, and pluggable hot-swappable components.

Downtime must be further minimized through on-line management capabilities such as on-line firmware upgrades, dynamic hardware and software reconfiguration, and application-transparent data movement.

Centralized management

In contrast to direct-attached storage architectures, SANs create a large virtualized storage pool that can be managed centrally to minimize storage management tasks, particularly in the areas of backup/restore and disaster recovery. Because SANs effectively provide a physical access path from all servers to all storage, security must be addressed. All storage should not be logically accessible to all servers.

SAN fabric vendors do this through the logical definition of "zones," with each server only able to access data defined as within its zone. Improved granularity of domain definition, such as defining a zone at the LUN--rather than port--level offers additional flexibility in improving storage asset usage.

However, probably the most critical capability a storage domain manager must offer is a set of centralized storage management capabilities that can be leveraged, from a single management interface, across all attached servers and storage, regardless of vendor.

If, from a central location, a system administrator can control the movement or mirroring of data between heterogeneous storage resources, and can dynamically leverage these capabilities across heterogeneous storage resources, a significant cost savings can result and the administrative complexity simplified.

Heterogeneous interoperability

With all the server and storage consolidation, as well as the mergers and acquisitions common in today`s new business climate, heterogeneity is a fact of life in enterprise environments. A set of products that provides SAN functionality for a single vendor`s product line is not sufficient for users to achieve the full promise of SANs.

In fact, this is the most compelling reason why a vendor-neutral management platform is required to implement heterogeneous SAN interoperability. Users need to be able to preserve investment in legacy equipment even as they add new server and storage products. As such, at a minimum a management platform must support Fibre Channel and SCSI, and it will need to accommodate new protocols in the future.

SANs offer a more flexible storage architecture that can help organizations meet the needs of today`s fast-paced business climate. However, to fully realize the promise of heterogeneous SANs, an intelligent, centralized management capability is required.

Click here to enlarge image

Advanced storage management functionality, such as a hot remote copy, can be leveraged against storage resources from vendors A and B, and then dynamically reconfigured to perform similar (or other) tasks between storage resources from vendors C and D. Multiple storage domain managers may be involved in a single operation.

Eric Burgener is director of product marketing at ConvergeNet Technologies Inc. (www.convergenet.com), in San Jose, CA.