IP Storage: Maximizing Investment

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The term “IP Storage” is generally used to refer to a storage area networking solution that uses standard Ethernet connectivity in some way. These solutions typically fall into one of the two categories: Those that use an Ethernet link to interconnect Fibre Channel SAN environments via gateways; and those where a SAN is built using Gigabit Ethernet infrastructure instead of Fibre Channel.

Consequently, IP, storage solutions typically extend and complement existing SAN environments, or they provide affordable new SAN storage solutions in parts of the IT infrastructure that are still dominated by direct-attached storage.

The benefits shared by all IP storage solutions derive from advantages associated with standard Ethernet networking:

Using IP Storage to Interconnect SAN Islands

Mature, well-understood technology with a long history of plug-and-play interoperability
Low costs through commodity economics
Strong roadmap to 40Gb and beyond
Reliable, fault-to learn, with built-in quality of service
Routable transport with no distance limitations
Flexible provisioning and configuration
A broad range of proven management tools
Enormous knowledge and experience base-expertise in every IT organization

Taken all together, IP, storage solutions greatly broaden the options available to IT executives to address the cost, availability, performance and manageability issues caused by continual, data growth, and to accelerate their transition from yesterday's direct-attached storage architecture to tomorrow's networked Storage model.

Interconnecting Fibre Channel SANs
Two IP storage-bridging protocols are available to provide the basis for interconnecting existing Fibre channel SAN environments. The use of IP networks here is typically to overcome the distance limitations of Fibre Channel; to provide lower cost solutions than using proprietary protocols over private fiber links; and to enable ubiquitous remote data protection and disaster recovery solutions.

T Typical IP SAN Environment using iSCSI

FCIP is a TCP/IP-based tunneling protocol designed to transparently provide point-to-point connections between geographically distributed Fibre Channel SANs using FCIP gateways to connect to an IP network. It is particularly well suited to provide connectivity to remote SANs for backup and restore, or remote data replication applications.

iFCP is a TCP/IP-based protocol for interconnecting storage devices or Fibre Channel SANs using an IP infrastructure. IFCP solutions consist of Fibre Channel end-points connected to an IP network by means of iFCP gateways. It is particularly well suited to providing the reliable transport of storage data suited between separate SAN domains via TCP/IP LAN, MAN or W WAN infrastructure.

IP-Native SANs
In contrast, the iSCSI protocol enables the creation of complete SAN solutions based on Gigabit Ethernet, instead of Fibre Channel, network infrastructure. iSCSI is simply the combination of two very well-understood technologies: SCSI block storage commands running over a TCP/IP transport. The iSCSI protocol is an industry standard protocol (RFC 3720) created, maintained and ratified by the Internet Engineering Task Force (IETF).

iSCSI is interesting as a SAN alternative to direct-attached storage in environments where simplicity attached simplicity, flexibility, price/performance, and availability of administrative staff are critical IT decision factors, iSCSI SAN solutions (often called IPSANs) consist of iSCSI initiators (software driver or adapter) in the application servers, connected to iSCSI storage systems by means of standard Gigabit Ethernet switches and cables.

IP SANs are deployed for all the same reasons that Fibre Channel SANs are typically deployed as an alternative to direct attached storage.

iSCSI provides the basis for SAN storage solutions (primary storage) in environments where it was not considered to be feasible or cost effective

According to IDC, the top reasons are:

Back: 46.0%
Storage consolidation: 40.0%
Satisfy on-going demands for additional capacity: 37.0%
Performance: 31.0%
Disaster recovery: 27.0%
New project or application deployment: 23.0%

Today backup and storage consolidation in the face of rapid, data growth are the primary reasons for considering an IP SAN, followed by the intention to implement an affordable disaster fordable recovery solution.

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