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Abstract
Storage area network (SAN) technology, once restricted to large organizations and mainframe environments, is becoming more common in mid-sized organizations that need to store and share access to large amounts of data. With the development of Internet SCSI (iSCSI) technologies, the benefits of SAN technologies are likely to extend even to small organizations.
This white paper describes how SANs are used with Windows products such as Microsoft Windows Server 2003 and Microsoft Windows Storage Server 2003, as well as with Microsoft Exchange Server 2003 and Microsoft SQL Server 2000. While the Windows operating system has been used in SAN environments since the introduction of Microsoft Windows Server NT 4.0, the release of Windows Server 2003 has dramatically enhanced SAN interoperability. That commitment to SAN interoperability will continue with future Microsoft releases.
Introduction
Storage area networks (SANs) are high performance networks dedicated to delivering block (unformatted) data between servers and storage. SANs originated in the 1980s as a mainframe solution designed to accommodate the then specialized need to store huge amounts of data in a manner that was scalable, flexible and highly available. Originally restricted to high end single vendor solutions, by 2003, with the rapid growth of the Internet and increased reliance on e commerce, adoption of SANs (often in multi-vendor configurations) has become more common. According to IDC ,the global market research firm for IT industries, SAN adoption has grown from a market share of a little over 20% in 2000 to nearly 45% in 2002. This growth has been at the expense of direct attached storage (DAS), which has declined in market share from 66% to 45% over the same time period. While no longer solely a high end solution (although the most advanced and fully developed SAN solutions are still to be found in mainframe environments), SAN adoption is predominantly found in organizations that need to store a terabyte or more of data .
As the need for more flexible and scalable storage solutions extended beyond the mainframe market to the open server market, it became clear that operating systems designed with the expectation that storage is local to the server would need to be extensively re-architected to allow customers to realize the SAN benefits of shared storage.
In the Windows environment, a number of changes were made to enable the operating system to function more effectively in a SAN environment. The first step in this process was to enable SAN connectivity. This advance was put into effect with the release of Windows NT Server 4.0. Since that release, Windows architecture has undergone continued development to enable more effective SAN use and performance. The improvements are the subject of this paper.
As a direct result of these advances, Windows use in the SAN market has dramatically increased. In Fibre Channel SAN environments, Windows adoption has grown from 26% of the market in 2000 to more than 40% by the end of 2002 . Most of that growth has happened in the lower price bands , and many analysts expect Microsoft support for iSCSI (which enables SANs using existing IP infrastructure) to continue to help drive SAN adoption over the next five years , particularly at the less expensive price ranges.
Storage Area Networks
Both direct attached storage and storage area networks use the SCSI protocol to move data in blocks, rather than files . In fact, from the vantage point of most operating systems, DAS and SAN storage are indistinguishable, despite the differences in their network topologies (see Figures 1 and 2). So what do storage area networks offer that traditional direct attached storage does not
SANs are designed to enable centralization of storage resources, while at the same time overcoming the distance and connectivity limitations posed by directly attached storage. Parallel SCSI interconnects limit direct attached storage devices to a distance of 25 meters, and can connect a maximum of only 16 devices. Fibre Channel SANs extend the distance limitation to 10 kilometers or more, and enable an essentially unlimited number of devices to attach to the network. These factors allow SANs to effectively uncouple storage from the server and to pool on a network where it can be shared and easily provisioned, without the problems of scaling associated with DAS.
read more
http://download.microsoftdownload/1/1/9/...20SANs.doc
http://download.microsoftdownload/8/3/5/...%20DAS.doc
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[attachment=7859]
Submitted by- Ramesh Chandora
Introduction
What is SAN (Storage Area Network) ? A storage area network (SAN) is a storage device (such as disk arrays, tape libraries, and optical jukeboxes) accessible to servers so the devices appear as locally attached to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the regular network by regular devices. The cost and complexity of SANs dropped in the late 2000s, allowing wider adoption across both enterprise and small to medium sized business environments. A SAN alone does not provide the "file" abstraction, only block-level operations. However, file systems built on top of SANs do provide this abstraction, and are known as SAN file systems or shared disk file systems.
Further Defining a SAN
A SAN allows a machine to connect to remote targets such as disks and tape drives on a network for block level I/O. From the point of view of the class drivers and application software, the devices appear as locally attached devices. A SAN consists of a communication infrastructure, which provides physical connections, and a management layer, which organizes the connections, storage elements, and computer systems so that data transfer is secure and robust. The term SAN is usually (but not necessarily) identified with block I/O services rather than file access services.
According to SNIA (Storage Networking Industry Association), SAN is:
1. The purpose of the SAN is transmitting data between storage systems and storage systems or storage systems and client servers.
storage systems to client, and then storage management devices, servers, and network devices. However, SAN is usually defined as block I/O services provider. 2. The storage system contains storage components, devices, computer equipments, software applications, and network devices.
SAN can be broadly classified into three layers: 1) Host Bus Adaptors- These refer to the host server that connected to the SAN network. They have the necessary interface to talk to the SAN network. The LANs/WANs will get the necessary information through the HBA 2) SAN Network - The SAN network is the interconnecting layer between the host servers and actual storage devices. The SAN network may be implemented using switched fabric loop (FC-AL) or point to point topologies. The SAN network components include bridges, adapters; media interface adapters, routers and Gigabit interface converters. Storage area networks enable a number of applications that provides enhanced performance, manageability and scalability. Some of these applications include true data sharing, data vaulting and backup, clustering, data protection and data recovery. 3) Storage Devices- These refers to the physical storage devices such as disks, RAID, tape drives, optical drives and other physical device where the data can be stored.
SAN Infrastructure
SANs often utilize a Fibre Channel fabric topology - an infrastructure specially designed to handle storage communications. It provides faster and more reliable access than higher-level protocols used in Network-attached Storage (NAS). A fabric is similar in concept to a network segment in a local area network. A typical Fibre Channel SAN fabric is made up of a number of Fibre Channel switches.
Today, all major SAN equipment vendors also offer some form of Fibre Channel routing solution, and these bring substantial scalability benefits to the SAN architecture by allowing data to cross between different fabrics without merging them. These offerings use proprietary protocol elements, and the top-level architectures being promoted are radically different. They often enable mapping Fibre Channel traffic over IP or over SONET/SDH
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Storage Area Networks (ppt)
The Storage Networking Industry Association defines Storage Area Networks as follows:
A network whose primary purpose is the transfer of data between computer systems and storage elements and among storage elements. Abbreviated SAN. A SAN consists of a communication infrastructure, which provides physical connections, and a management layer, which organizes the connections, storage elements, and computer systems so that data transfer is secure and robust. The term SAN is usually (but not necessarily) identified with block I/O services rather than file access services.
A storage system consisting of storage elements, storage devices, computer systems, and/or appliances, plus all control software, communicating over a network.
SANs originated in the 1980s as a mainframe solution to storing large amounts of data that was scalable and flexible with highly availability.
Storage area networks (SANs) are high performance networks dedicated to delivering data between servers and storage.
ARCHITECTURE
A SAN consists of a communication infrastructure, which provides physical connections, and a management layer, which organizes the connections, storage elements, and computer systems so that data transfer is secure and robust.
Centralized and interconnected storage devices reside in the bottom tier of the traditional 3-tiered client/server architecture.
Fibre Channel is the most widely used SAN technology because of its speed, scalability and flexibility.
A SAN is typically based on one of two topologies:
Arbitrated Loop is a classic ring topology that manages traffic flow. It is a fairly inexpensive configuration for small and medium sized SANs.
Switched Fabric provides full duplex communication between all devices in the SAN. Fabric switches are considerably more expensive than an arbitrated loop hub, but can provide each device on the SAN an independent connection to every other device.
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INTRODUCTION
The recent explosion in e-business activity and internet commerce has provided organization with unlimited opportunities for developing new information delivery channel. Data is today perceived to be the key asset for many organizations such as banking, stock exchange, government record etc. This has generated an explosive demand for data storage and this demand can be addressed by deploying SAN. The activity to share a single large storage device across many server or application has made SAN an attractive option in today s market place.
As organization continue to broaden there reach to business partners and customers around the globe, they expose key IT system to a wider range of potential security threats. Today data theft, fraud, hacker attempts, and human error increasingly threaten security of information exchange within the enterprise and across the public networks, such as the internet. In order to protect the key data stored, storage networking venders are rapidly deploying and developing security frameworks that help ensure safe reliable data processing throughout a storage area networks(SAN).
The most common thing to remember about SAN security is that SAN is a network and is vulnerable to the same sorts of vulnerabilities and attacks that more conventional computers are. SAN resources can be protected by physical security and the hosts on the SAN should be expected to meet stringent security requirements. As SAN continue to grow, it will become a bigger target for malicious attackers. In this section we will examine the emergence and evolution of the fiber channel protocol in the context of storage network technology.
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Introduction to Storage Area Networks
Historic trends
From mainframe to client server (1980 2000)
From client server to .. (2000 )
Peer to peer
Datacenters
Not clear who will be the winner (if there will be a single one)
Datacenter consolidation
Storage
More flexibility in using storage space
Disk not tied to computational resources
Computational resources
More flexibility
Power consumption
The storage evolution:outline
Direct Attached Storage (DAS)
Small Computer System Interface (SCSI)
Network Attached Storage (NAS)
Storage Area Network (SAN)
SAN architectures
Ethernet TCP/IP
I SCSI
FC IP
Fibre Channel
Complexities and performances
Fibre Channel vs. Ethernet
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