Beyond storage consolidation: the benefits of iSCSI SANs

Computer Technology Review, Feb, 2005 by Eric R. Schott

Managing storage and reducing administrative costs are at the center of an increasingly complex problem challenging small and large businesses. Today, most data centers have storage directly connected to individual servers. Direct attached storage (DAS) is expensive, difficult to grow, and limited in management capabilities--especially as servers proliferate.

SANs provide a solution to many storage management challenges via the ability to consolidate storage for many servers in a centrally managed resource. However, until mid-2003, IT managers had considerable obstacles to contend with since Fibre Channel was the sole means for implementing a SAN. While justifiable for large enterprises. FC-SANs come with significant initial and ongoing costs as well as administrative and management complexities that most enterprises cannot justify. The arrival of Ethernet-based SANs and the iSCSI standard changed the SAN playing field and made the benefits of consolidated storage available to businesses of all sizes.

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By combining the simplicity of Ethernet networks with the advanced storage features mission-critical applications require, iSCSI SANs deliver simplified storage management and consolidation at a reasonable price. The key to controlling costs and increasing storage management can be found in a SAN solution that couples best-of-breed consolidation and virtualization methods with iSCSI connectivity. Storage consolidation expands device connectivity and reduces points of management; virtualization delivers a centralized, flexible method of management that masks the complexity of storage infrastructures and reduces administrative overhead.

Storage Consolidation

Storage consolidation is an architecture that allows storage devices and servers to be acquired, managed and upgraded independently. In a consolidated storage environment, numerous heterogeneous servers and applications share a single pool of storage on a network. A consolidated infrastructure can lower management costs and results in easy scalability, high availability and efficient storage space utilization. It also simplifies backup and disaster-recovery strategies. An additional benefit of consolidated storage is that costs can be divided between various departments and groups using the storage. Increasingly, businesses are turning to iSCSI SANs to consolidate storage based on the solution's cost effectiveness, ease of use and block-level support. Figure 1 is an example of a consolidated solution.

Today, IT departments need a consolidated storage solution for their critical applications which provides the same functionality as high-end solutions made for mission-critical applications--but at a significantly lower cost and without excessive administrative over-head. To lower the total cost of ownership of the IT infrastructure, organizational storage costs must be parallel to their application and hardware investments. iSCSI SAN vendors are tackling this opportunity by delivering cost-effective solutions for storage and protection of data.

Vendor solutions in this emerging market vary in the level of features and capabilities offered, so IT managers should create a checklist of key capabilities for their iSCSI SAN, including: seamless expandability, automatic load balancing, automatic storage provisioning, disaster tolerance, and replication. iSCSI SANs are an ideal solution for data centers seeking to move away from DAS and realize the advantages of consolidated storage without the complexity and cost of conventional high-end, FC SANs.

Virtualization

Once storage is consolidated, the job is only half done because users still need a way to manage the storage. Enter virtualization. The goal of virtualization is to make a complicated task easy to perform. For example, operating system technologies utilize virtualization in a variety of areas, including the evolution of memory management from a manual process to a virtual memory subsystem that dynamically allocates memory as needed. Similarly, virtualization helped e-mail communication gain mass usage by allowing users to simply type the destination address, eliminating the need to understand network routing schemes.

As with memory management and e-mail, storage virtualization seeks to simplify unwieldy tasks such as setup, storage allocation, load balancing, RAID configuration, backup, replication, and snapshots. True virtualization takes storage administrators away from physical layouts and constraints of the underlying storage hardware. The decoupling of physical storage from logical volumes makes these normally disruptive activities transparent to hosts. By disassociating the physical disks from the logical volumes presented to hosts, administrators are no longer bound by disk capacity and performance, nor are they forced to cable or layout data across devices every time workloads change.

While the goal of virtualization is to simplify storage management, not all solutions achieve this objective effectively. Early-generation storage virtualization products deliver flexibility; however, they do little to reduce complexity. In fact, many of these products require extensive administrator involvement and increase the number of components an IT administrator must manage, load balance, configure, and provision.