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The demands on Storage Area Networks (SANs) go far beyond where they were only a few years ago. It is no longer good enough to just provide a large pool of scalable storage with good performance. Corporate users require easy and rapid access to data that may be globally distributed. IT managers must deliver on these requirements; ensure rapid disaster recovery capabilities, and accomplish it without breaking the bank. The five key factors defining today's metrics for a successful, global, enterprise SAN deployment are cost: bandwidth, reach, latency, and ease-of-access.
While Fibre Channel (FC) has satisfied the early demands for SANs, the evolution of the Internet Small Computer Systems Interface (iSCSI) and 10 Gigabit Ethernet (GbE) from Neterion have enabled a compelling alternative for building Global SANs.
10 GbE iSCSI Full Error Recovery And Distance Advantages
The completion of the entire iSCSI protocol, as defined by IETF RFC 3720, provides the full error recovery features as required by storage managers. These enhancements ensure robust and highly-available system operation across geographically diverse enterprise networks. The maturity and robustness of iSCSI with Error Recovery Level 2 (ERL 2) support, combined with the throughput, distance, and economy of scale advantages of Neterion's Xframe 10 GbE solutions, present a complete framework for deploying globally dispersed, ubiquitous, enterprise SANs. The key points are:
- Ethernet offers seamless integration with the LAN, MAN, and WAN, enabling native sharing of data anywhere in the world.
- Ethernet is based on wellproven protocols, management tools, with a wealth of trained experts worldwide.
- 10 GbE continues to benefit from emerging Ethernet advancements, such as hardware-based iWARP support (RDMA over TCP/IP) that further optimizes performance and reduce CPU utilization.
- True QoS functionality enables traffic to be consistently classified, prioritized, and queued at line rate speeds
- 10 GbE coexists natively with currently deployed 1 GbE infrastructures.
Furthermore, 10 GbE iSCSI SANs are not subject to distance limitations like FC-based SANs. Fibre Channel was designed as a campus- wide network, not to exceed 100 miles, and because of its sensitivity to delay; there are many issues with supporting it over WANs. These limitations negatively impact network costs making it very difficult to cost-effectively provide global access to a FC SAN.
Total Cost of Ownership Advantages
Calculating TCO for a SAN requires evaluation of more than just initial hardware costs. All costs including initial capital expenditures, maintenance fees, systems integration and management, ongoing support, physical space, port density, power, cooling, upgrades along with soft costs (e.g., slow network performance and downtime due to overloading) must be considered. There are always costs with deploying SANs, but the real differences are the costs of staffing, training, and managing a FC SAN versus iSCSI. Because Ethernet is already wide spread in the data center, the incremental management costs with 10 GbE iSCSI are negligible in comparison. Additionally, the simplification stemming from a converged Ethernet network results in savings on other hidden costs like downtime, problem tracking, and resource drains. Although these costs can be difficult to quantify, they are very real and can drive up the TCO. In fact, annual recurring management costs can range from 30% to 50% of the initial hardware investments.
Optimized Efficiency and Consolidation Advantages
Since iSCSI can be implemented at the software layer, existing servers can be upgraded with off-the-shelf iSCSI software with ERL 2 support allowing them to become a member of the SAN. Upgraded servers with 10 GbE Neterion Xframe adapters enables a single, high performance, easily managed IP network for data and storage. The virtualization capabilities on an Xframe adapter also ensure that IT managers have the most power to manage bandwidth for best performance. Another key advantage of 10 GbE iSCSI over FC is the management of bandwidth. Both iSCSI and FC are block level protocols (as opposed to file-level protocols like NFS/CIFS), but unlike FC, where unused bandwidth in a dedicated channel is wasted, complete iSCSI implementations with ERL 2 can optimize bandwidth usage by automatically allocating bandwidth from unused connections. The potential for consolidation savings are also significant.
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