COEN 180

NAS / SAN

NAS Network Attached Storage (NAS)

Each storage device has its own network interface.

Filers: storage device that interfaces at the level of a distributed file system.

Network File System: NFS (Unix) Common Internet File System CFIS (MS Win)

Flexible. Sharing of storage. Vulnerable. Sharing network makes megatasks such as back-

up difficult.

NAS

NAS

Trends favoring NAS: Storage devices become more

intelligent. Object based storage.

Storage devices become application aware.

NAS Advantages

NAS devices are stand-alone. Have their own OS, networking,

integrated hardware, and software. NAS devices offer shared storage,

accessible from a number of platforms.

NAS devices can easily be added on to an existing network.

SAN

Storage Area Networks Low costs High transfer Use a dedicated network.

SAN

SAN Host Layer

Consists of storage servers and components necessary to connect to SAN.

HBA Gigabit Interface Converter (GBIC) /

Gigabit Link Converter (GLC) Host Bus Adapter Drivers Cables

SAN

Network Technology Fibre Channel IP over Ethernet.

SAN Gigabit Interface Converter

Converts to optical fiber. Short wave:

Laser frequency between 780 and 850 nm. Used for distances between .5m and 500m.

Long wave: Laser frequency at 1300 nm. Used for distances between 2 m and 10km. Newer long-wave GBIC up to 100 km.

SAN

Full duplex transmission

SAN Fabric Layer

Contains the components necessary to connect storage servers with storage devices.

Hubs Switches Routers:

Bridge between SCSI and Fibre Channel Cables

SAN

Storage Layer Monolithic

Large with many disk drives Modular

Controller shelf plus single shelf of disks. Add more shelves as needs grow.

SAN

Storage Array Manufacturers Mainframe Class

Hitachi IBM EMC

Modular Class Hitachi Compaq Hewlett Packard EMC IBM XIOtech LSI Logic Sun Microsystems MTI

Fibre Channel Basic Fibre Channel Topologies

Point to Point Switched Fabric Arbitrated Loop.

Fibre Channel

Point-to-point Eliminates need to invest in fabric

Other than cables. Storage devices have more than one

port and can connect to as many servers as they have ports.

Fibre Channel

Arbitrated Loops Physically, consists of Fibre Channel

hubs. Internally, uses the FC-AL protocol.

Fibre Channel Arbitrated Loop. Can deal with 128 devices. But looses performance much earlier.

Fibre Channel Switched Fabric

Switches come in Modular class

8 – 16 ports. Multiple fans, power supply, etc. Single controller component

A single point of failure. Director class

32, 64, … ports Blades of ports.

Redundant components.

Fibre Channel

Switched Fabric Run at 1Gb/sec Run at 2Gb/sec Will run at 10Gb/sec

Fibre Channel

Switched Fabric Different Topologies

Dual switches Loop of switches Meshed fabric Star Core-edge

switch

switch

Fibre Channel Fibre Channel Protocol

FC-4: Upper Layer Protocol Interface supports VI, IP, and most importantly, serial SCSI-3 (FCP). The task of FCP is to make fibre channel devices appear as standard SCSI devices to each other. This strategy avoids OS modifications in the storage servers.

FC-3: Common Services, is currently under development and will contain such services as striping a transmission over several ports, hunt groups that allow more than one port to respond to the same alias address (in order to decrease chances of hitting on a busy port), and multicasting.

FC-2: Data Delivery codifies framing, flow control and service class. A fibre channel frame consists of 32B frame meta data framing a 2112 B data field that contains up to 2048B payload. The fiber channel service classes allow either an in effect a virtual physical connection (class 1), or packet switched connections with (class 1) or without (class 2) acknowledgments.

FC-1: Ordered sets / byte encoding. FC-0: Physical interface (optical/electrical, cable plant).

Fibre Channel

SAN /NAS