Keith Spayth ACSG 520 Dr. Alzoubi Storage Area Networks Keith Spayth ACSG 520 Dr. Alzoubi

Storage Area Networks - Defined 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.

Storage Area Networks - 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.

Storage Area Networks – Benefits Using a SAN can potentially offer the following benefits: Improvements to application availability: Storage is independent of applications and accessible through multiple data paths for better reliability, availability, and serviceability. Higher application performance: Storage processing is off-loaded from servers and moved onto a separate network. Centralized and consolidated storage: Simpler management, scalability, flexibility, and availability. Data transfer and vaulting to remote sites: Remote copy of data enabled for disaster protection and against malicious attacks. Simplified centralized management: Single image of storage media simplifies management.

Storage Area Networks - Considerations Data format Data can be stored as files, or in block format. SAN management architecture SAN storage level SAN network level Enterprise systems level Security Security in a LAN environment can be complex. When utilizing multiple storage servers, it is critical that one server cannot overwrite another's information. Access control is also extremely important.

Storage Area Networks – Management SAN Storage Level Consists of storage devices such as disks, disk arrays, tapes and tape libraries. The ANSI SCSI-3 serial protocol is used by many SAN vendors in order to offer higher speeds, longer distances, and greater device population for SANs, with few changes in the upper level protocols. This protocol defines a new set of commands called SCSI Enclosure Services (SES) for basic device status from storage enclosures.

Storage Area Networks – Management SAN Network level Consists of SAN cables, SAN hubs, SAN switches, inter switch links, SAN gateways, and Host bus adapters (HBAs). Closely tied to local area network (LAN) and wide area network (WAN) infrastructures. The hubs, switches, gateways, and cabling use Simple Network Management Protocol (SNMP) to manage all of these networking components. Most SAN solution vendors require SNMP support to be used by SNMP based network management applications.

Storage Area Networks – Management SAN Enterprise level The enterprise systems level essentially ensures the ability to have a single management view and console. Enterprise systems management applications gather and present all management data in a single web-based management tool. Data comes storage devices, networks, servers, and desktops. Common interfaces include: Web-Based Enterprise Management Common Information Model Application Program Interface Java Management API Desktop Management Interface

Storage Area Networks – Security A storage device is connected to many systems, and must protect: Confidentiality of data Integrity of data Against unauthorized deletion of data Loss of access to data

Storage Area Networks - Security Recommended steps to minimize the risks : Authentication Administrative tasks require administrator log in access. Devices must log in to the storage network before gaining access to the data. Authorization Individual administrators have permissions to only perform specific actions on specific devices. Storage devices validate rights to data to prevent access from an unauthorized source. Audit All administrative changes and significant events are logged to track changes and trace problems. Encryption (not yet in widespread use) Protects both confidentiality and integrity of data.

Storage Area Networks – Network Technologies Current Technology Fibre Channel Emerging Technologies iSCSI Fibre Channel over IP Fibre Channel over ATM Fibre Channel over SONET Fibre Channel over dark fiber or DWDM

Storage Area Networks – Fibre Channel Fibre Channel is the predominate SAN technology since it: Provides a high-speed, non-blocking architecture Scales from 133 Mbps to 1 Gbps and beyond Allows different high-level protocols (IP, ATM, etc.) to operate over its infrastructure Can connect nodes up to 10 kilometers (over 6 miles) apart. Fibre Channel can attach devices through a number of methods like loops, hubs, and switches. Hubs make loop simulate a series of point-to-point connections. Switches permit multiple devices to be connected via multiple loops, thereby multiplying bandwidth. Multiple 100-MBps loop configurations can be managed through one central point. Fabrics, composed of multiple switches, enable Fibre Channel networks to grow to very large sizes, that offer extremely high bandwidth. Fabrics can span very large geographic areas. These features make fibre channel a fast, stable, and flexible technology for storage area networks.

Storage Area Networks – FCIP Fibre Channel over IP combines proven technologies to accomplish the transfer of storage data within SAN. Fibre Channel provides software compatibility, interoperability, and proven applications for storage networking. IP facilitates the movement of data across WANs and is a proven application for WAN-based data networking. Fibre Channel over IP solutions enables Fibre Channel frames to be encapsulated in TCP packets that are transported over the IP network. Overall performance is dependent on the types of switches and routers, the number of hops and the amount of congestion in the network. Fibre Channel over IP is currently a very cost-effective technology for asynchronous applications such as remote data backup. The IETF standards organization is currently developing specifications to allow the transport of Fibre Channel data over IP networks.

Storage Area Networks – iSCSI iSCSI is an emerging standard which defines the encapsulation of SCSI packets in TCP. These packets are then routed using IP. This technology allows block-level storage data to be transported over widely used IP networks, enabling end users to access the storage network from anywhere in the enterprise. Several iSCSI products are now available, including iSCSI HBAs and iSCSI- to-Fibre Channel storage routers. Storage routers, when utilized with a Fibre Channel switch, will enable block-level storage traffic to be accessed from a SAN over an IP network. The iSCSI concept can be expanded to create a storage network by using any network-connected device. iSCSI enables HBAs to provide I/O processing on order to reduce the load on the server CPU.

Storage Area Networks - Conclusion Benefits for SANs include Improved application availability Increased application performance Centralized storage Centralized management SAN architecture and management are still evolving. Emerging technologies such as FCIP and iSCSI are based on existing, proven technologies. SANs components and technologies are being developed which will reduce overall costs. Management will continue to evolve with a goal of supporting a heterogeneous multi-vendor SAN that would work with components from any vendor.

Storage Area Networks - Bibliography Introduction to Storage Area Networks, http://www.redbooks.ibm.com/redbooks/pdfs/sg245470.pdf, March 2003 Windows Servers in a Storage Area Network Environment White Paper, http://download.microsoft.com/download/1/1/9/119ed79d-3e58-4452-be36-f28325805857/MS%20SANs.doc, April 2004 A Dictionary of Storage Networking Terminology: Common storage networking-related terms and the Definitions applied to them, by the Storage Networking Industry Association, http://www.snia.org/education/dictionary/s/#storage_area_network The Emerging FCIP Standard for Storage Area Network Connectivity Across TCP/IP Networks, http://www.snia.org/ipstorage/about/fcip/FCIP_whitepaper.pdf, June 2001 Storage Area Networks: An Essential Guide to SANs as a Component of Business Continuation, by Mark Steinberg, http://www.hill.com/archive/pub/papers/papers.asp?yr=2002&mn=09, September, 2002 Storage Area Networks, http://www.saiitstorm.com/website3rd/storagenetwork.htm Storage Networking with Fibre Channel& IP Networks, http://www.iscsistorage.com/wp/papers/fcip.pdf, June 2004 Storage security: Emerging storage networking topic of interest, http://i.i.com.com/cnwk.1d/html/itp/77_StorageSecurity.pdf, May 2004 Fibre Channel vs. SCSI: Which is more advantageous for your storage area network?, http://sunsite.uakom.sk/sunworldonline/swol-03-1999/swol-03-fibre-scsi.html, March 1999