SAN TUTORIAL by Manhattan Skyline GmbH

MSKL SAN Tutorial

1. What is a SAN?

A SAN, or storage area network, is a dedicated network that is separate from LANs and WANs. It generally serves to interconnect the storage-related resources that are connected to one or more servers. It is often characterized by its high interconnection data rates (Gigabits/sec) between member storage peripherals and by its highly scalable architecture. Though typically spoken of in terms of hardware, SANs very often include specialized software for their management, monitoring and configuration. SANs can provide many benefits. Centralizing data storage operations and their management is certainly one of the chief reasons that SANs are being specified and developed today. Administrating all the storage resources in high-growth and mission-critical environments can be daunting and very expensive. SANs can dramatically reduce the management costs and complexity of these environments while providing significant technical advantages. SANs can be based upon several different types of high-speed interfaces. In fact, many SANs today use a combination of different interfaces. Currently, Fibre Channel serves as the de facto standard being used in most SANs. Fibre Channel is an industry-standard interconnect and high-performance serial I/O protocol that is media independent and supports simultaneous transfer of many different protocols. Additionally, SCSI interfaces are frequently used as sub-interfaces between internal components of SAN members, such as between raw storage disks and a RAID controller.

MSKL SAN Tutorial

Provding large increases in storage performance, state-of-the-art reliability and scalability are primary SAN benefits. Storage performance of a SAN can be much higher than traditional direct attached storage, largely because of the very high data transfer rates of the electrical interfaces used to connect devices in a SAN (such as Fibre Channel). Additionally, performance gains can come from opportunities provided by a SAN’s flexible architecture, such as load balancing and LAN-free backup. Even storage reliability can be greatly enhanced by special features made possible within a SAN. Options like redundant I/O paths, server clustering, and runtime data replication (local and/or remote) can ensure data and application availability. Adding storage capacity and other storage resources can be accomplished easily within a SAN, often without the need to shut down or even quiese the server(s) or their client networks. These features can quickly add up to large cost savings, fewer network outages, painless storage expansion, and reduced network loading. By providing these dedicated and “very high speed” networks for storage and backup operations. SANs can quickly justify their implementation. Offloading tasks, such as backup, from LANs and WANs is vital in today’s IT environments where networks loads and bandwidth availability are critical metrics by which organizations measure their own performance and even profits. Backup windows have shrunken dramatically and some environments have no backup windows at all since entire data networks and applications often require 24x365 availability. As with many IT technologies, SANs depend on new and developing standards to ensure seamless interoperability between their member components. SAN hardware components such as Fibre Channel hubs, switches, host bus adapters, bridges and RAID storage systems rely on many adopted standards for their connectivity. SAN software, every bit as important its hardware, often provides many of the features and benefits that SANs have come to be known for. SAN software can provide or enable foundation features and capabilities, including: • • • • • • • • SAN Management SAN Monitoring (including “phone home” notification features) SAN Configuration Redundant I/O Path Management LUN Masking and Assignment Serverless Backup Data Replication (both local and remote)