Storage Area Network (SAN) Presenters: Arun Kumar Kamepally Udaya Tummala

Contents Introduction RAID SAN definition SAN Environment SAN components SAN topologies Difference between NAS,DAS,SAN SAN management

Introduction Data has became more important and technology has become obsolete to handle huge data. Traditionally local storage devices are used to store data. Later storing data centrally and making it available has become cost effective to handle data. Network storage is simply about storing data using a method by which it can be made available to clients on the network. Different Storage technology DAS NAS SAN

Storages RAID: RAID is a method used to inexpensively put together a set of physical hard drives into a logical array of storage devices. RAID provides fault tolerance compared to standalone disk drives. RAID does this by mirroring data or implementing parity check operations. RAID can be performed using hardware or host based software. Several types of RAID can be used, including one or more of these RAID 0 (striping) RAID 1 (mirroring) RAID 3 (error detection) RAID 5 (error correction)

Definition A SAN is a High- speed Special Purpose Network that interconnects different kinds of data storage devices with data servers. Hubs, switches and bridges are used for connecting to different devices. SAN is very expensive only big businesses can afford it.

SAN is a Network that transfer data between storage devices like disk array and servers. SAN work same as Server in different way. Data is stored in Disk Array. SAN is useful for getting server backup SAN is a set of protocols and technologies that permit storage devices to have direct connections with servers over some distance. In addition, a SAN permits the storage devices to be shared among a number of servers based on select criteria. VSAN technologies, a group of discrete SANs can be connected together using a “ virtual “ SAN fabric.

What makes SAN? Storage Devices High Speed Connectivity SAN Software SAN Management

Continue……. A SAN can be used to bypass traditional network bottlenecks. It supports direct, high speed data transfers between servers and storage devices in the following three ways: Server to storage: This is the traditional model of interaction with storage devices. The advantage is that the same storage device may be accessed serially or concurrently by multiple servers. Server to server: A SAN may be used for high-speed, high-volume communications between servers. Storage to storage: This outboard data movement capability enables data to be moved without server intervention, thereby freeing up server processor cycles for other activities like application processing.

Technologies in SAN: Multiple technology can be used when building a SAN; traditionally the dominant technology is Fiber Channel, but Ip based solutions are also quite popular for specific applications. The concept of SAN is also independent from the devices that are attached to it. Can be disks, tapes, RAIDs, file servers or other. Hubs, switches and bridges are used for connecting to different devices.

SAN components Fibre Channel Network: A high performance (200 MB/sec) redundant network made up of fibre channel switches for deploying and sharing enterprise resources. Host Bus Adapter (HBA): PCI adaptor connects a server to the SAN fabric. Each HBA installed is referred to as a host. Enterprise Storage: Any storage device with FC interface that is interoperable with the switches, HBAs, servers and server operating systems in the network

SAN Advantages: SAN Architecture facilitates scalability. Storage devices can be added to store hundreds of terabytes. Sharing SAN is possible. SAN is not directly attached with any particular server or network, SAN can be shared by all. SAN provides long distance connectivity. SAN is truly versatile. A SAN can be single entity , a master grouping of several SANs.

SAN,NAS,DAS SAN is a block device which is delivered over the network. Like DAS you must still place a file system upon it before it can used. Technologies to do this include Fibre Channel, iSCSI, FoE, etc. NAS is a file system delivered over the network. It is ready to mount and use. Technologies to do this include NFS, CIFS, AFS, etc. DAS is a block device from a disk which is physically [directly] attached to the host machine. You must place a file system upon it before it can be used. Technologies to do this include IDE, SCSI, SATA, etc.

Supported topologies by SAN Point to point Arbitrated loop Switched Fabric Point to point: Point to point is the simplest topology with lited connectivity needs It guarantees in delivery and full bandwidth access. Application can handle any multipath connectivity to a set of disks in case this is provided, since no other elements are present in this topology.

Arbitrated loop: Designed to scale to a limited number of nodes. Low cost Arbitration protocols designed to manage media sharing across nodes may be disruptive when a node gets added/ removed from loop and loop initialization protocol kicks in A arbitrating hub can be used instead of a distributed protocol Switched Fabric: In this switching element get added to allow interconnections via point to point links. Extended number of devices and greater distances can be achieved Scalable, robust and reliable architecture.

SAN management Storage level : is comprised of the storage devices that integrate the SAN, such as disks, disk arrays, tapes, and tape libraries. Network level: is comprised by all the components that provide connectivity, such as cables, switches, inter-switch links, gateways, routers. Enterprise Level: comprises all devices and components present in a SAN environment, as well as the workstations indirectly connected to it

References [1] Rabe, Bruce R., Mark Clifford, and Norm Miles. "Storage area network (SAN) management system for discovering SAN components using a SAN management server." U.S. Patent No. 7,194,538. 20 Mar. 2007. [2] Sacks, David. "Demystifying Storage Networking DAS, SAN, NAS, NAS Gateways, Fibre Channel, and iSCSI." Published by IBM storage networking(2001). [3] Clark, Tom. Designing Storage Area Networks: A Practical Reference for Implementing Storage Area Networks. Addison-Wesley Longman Publishing Co., Inc., 2003. [4] Khattar, Ravi Kumar, et al. Introduction to Storage Area Network, SAN. IBM Corporation, International Technical Support Organization, 1999.