Storage Networking

1. Storage Networking By James A Pendleton, Jr.

2. SAN Characteristics Benefits Disadvantages NAS Characteristics Benefits Disadvantages Types of Storage area Networks • Others: DAS, IAS, etc.

3. General SAN Components • FC Switch • Host Bus Adapter • ISL(s) • Attached Storage

4. SAN Topology • 5 Primary Types • Star (hub-and-spoke) • Linear (bus/cascade) • Circular (ring/loop) • Tree • Mesh • Full Mesh • Partial Mesh • Six primary topologies can be combined to form a hybrid topology.

5. Star In a Star Topology, all devices are connected to a central hub. They are relatively easy to install and manage, but bottlenecks are common because of the need for all data to pass through the hub. The central hub can also stand as a single point of failure. One work around for this is to distribute the star network across multiple hubs.

6. Linear A Linear Topology has all devices connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems tend to use a bus topology, as do most mainframes. They tend to not scale too well. You can minimize problems with scalability by distributing the network.

7. Circular Circular Topology connects all devices to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances.

8. Tree A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies are highly edge-core friendly. Core-edge design is used to build a large san using small switches. They can be expensive and complex to implement and maintain. Strict tree has a problem with redundancy so ISLs are used to eliminate Point of Failures.

9. Full mesh topology occurs when every node has a circuit connecting it to every other node in a network. Full mesh is very expensive to implement but yields the greatest amount of redundancy, so in the event that one of those nodes fails, network traffic can be directed to any of the other nodes. Full mesh is usually reserved for backbone networks due to price. Partial mesh topology is less expensive to implement and yields less redundancy than full mesh topology. With partial mesh, some nodes are organized in a full mesh scheme but others are only connected to one or two in the network. Partial mesh topology is commonly found in peripheral networks connected to a full meshed backbone. Mesh Topologies

10. Network Reference Model • The OSI Reference model • Layer 1 - physical layer: • Layer 2 - data-link layer • Layer 3 - network layer • Layer 4 - transport layer • Layer 5 - session layer • Layer 6 - presentation layer • Layer 7 - application layer

11. OSI in action: Web Page

12. It is not required that that each device meets every layer, in fact many devices do not. OSI in a network

13. Physical Restrictions Data Locality Connectivity Capacity Heterogeneous [het-er-uh-jee-nee-uh s] Platforms& O/S Scalability and Migration Backup and Restore Data Availability Disaster Tolerance Switch and Hop Counts Oversubscription Performance and Application workloads Manageability Fabric Zoning Selective Storage Presentation SAN Security Approach to engineering a SAN:

14. What usually overrides all correct and logical engineering decisions: