Sunday, December 13, 2009

1. What is a SAN?

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
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
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)
· Shared Storage (including support for heterogeneous platform environments)

to be cntnd..