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PROTOCOLS USED IN STORAGE NETWORKING

networking

Fiber Channel:  Fiber Channel is a switched fabric, storage networking solution. As the pre-eminent storage area network (SAN) protocol in enterprise data centers, Fiber Channel has a 20+ year track record of successfully supporting Tier 1 applications.  Fiber Channel was specifically designed as a block-based protocol to meet storage area network needs, and as we’ll see, provides the reliability, performance, scalability, flexibility and management capabilities that both enterprises and mid-sized organizations demand for their production storage.

iSCSI: First introduced in 2001, iSCSI is an IP-based storage networking standard that supports block- based storage. Most commonly hosted on Ethernet, iSCSI runs on a mixed data (LAN) and storage (SAN) network. iSCSI was originally designed as a lower cost, simpler to manage SAN alternative that can leverage customers’ Ethernet investments, and has found strong acceptance as a storage solution in the mid-market.

NAS/NFS: Network Attached Storage protocols such as NFS and CIFS are file-based rather than block- based, but like iSCSI, they generally run on Ethernet and TCP/IP stacks. Rather than running in a SAN architecture, NAS systems are usually implemented as separate appliances that provide file-based data storage services to servers and other devices on an Ethernet network. Given their IP networking roots, NAS protocols such as NFS trade off some reliability and performance, but can be attractive from a cost and manageability standpoint.

Infiniband: Infiniband is a switched fabric interconnects architecture for servers, which has found its sweet spot in clustered high performance computing (HPC) environments. More recently, Infiniband has also begun to find adoption in SANs. Like  Fiber Channel, Infiniband is designed for scalability, reliability and performance, though it has achieved limited adoption and visibility to date in the enterprise data center. However, Infiniband is beginning to make inroads into more mainstream, critical application environments, and has already found broad unrecognized use among the internal subsystems of compute and storage appliances that often reside in the data center.

Fiber Channel over Ethernet (FCoE): FCoE is a network technology that encapsulates Fiber Channel frames over Ethernet networks. FCoE is designed as a “convergence protocol”, enabling Fiber Channel SAN traffic and IP data network traffic to co-exist on a single network. To enable reliability and quality of service, FCoE must run with “lossless”, Data Center Bridging (DCB) Ethernet, a set of enhancements that provide for congestion management, bandwidth partitioning and priority-based bandwidth allocation on an Ethernet LAN. FCoE is not yet widely deployed outside of blade server environments, but is expected to gain traction as more companies move to converged networks for some of their less critical assets.

In addition to these five major storage network solutions, a few other “hybrid” technologies have recently emerged. Several of these utilize RDMA, a technology that enables peer-to-peer, remote direct memory-to-memory access, which is particularly useful in HPC applications. Examples include iSCSI Extensions for RDMA (iSER), which maps the iSCSI protocol over RDMA; and RDMA over Converged Ethernet (RoCE), a network protocol that allows RDMA over DCB (lossless) Ethernet networks by running the Infiniband transport protocol using Ethernet frames. RoCE is limited to Ethernet speeds and is best used in environments such as HPC that do not require routing. RoCE is not designed to run optimally in a traditional storage area network environment.

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