SAN_Basics.ppt

transcript

VERITAS Technical Support

Basic Fibre Channel

Storage Area Networking

VERITAS Confidential 2

What time is it?

This course is designed to cover the following objectives:

Module 2: Networking & Storage.

This module begins with an introduction to the background of networking and data storage. Front end networks, the SCSI bus, network attached storage (NAS) and back end networks are described.

Module 3:Fibre Channel Architecture.

This module covers provides an in depth overview of the architectural structure of the Fibre Channel protocol

.Module 4:SAN Topologies.

This module explains the various connectivity methods used in the SAN environment. Point to Point, Arbitrated Loop and Fabric (switched) topologies are discussed.

Module 5: SAN Hardware Products.

This module provides an introduction to the most common SAN hardware products in use today. Host Bus Adapters (HBA’s), Raid/Fibre disks, Hubs, SCSI to Fibre Bridges and Fabrics (switches) are presented.

Module 2

Networking & Storage

Serial & Parallel TransmissionsSerial & Parallel Transmissions

2 .3 .B NETWORK ACCESS.Gaining access and/or control of the network iscontrolled regardless of the transport method used.Ethernet, the most common transport method in aFront End network, uses an access method known ascarrier sense multiple access and collision detection(CSMA/CD). The server, or node that wants to transmit data, “listens” for the presence of another transmission on the wire. Actually it’s sensing the presence of a particular voltage level. If another transmission is not detected, the node sends its data.

NETWORK ADDRESSING.

All communication adapters are encoded with a unique address at the time of manufacture. Each manufacturer is assigned a range of addresses. This is commonly referred to as the Media Access Control (MAC) address and is 6 bytes long. (4 bits = 1 byte).

In order to participate on a network such as the IP network, each node must be assigned a unique Internet Protocol (IP) address which consists of 16 bytes divided into 4 byte positions known as octals. Each octal position is equal to one of the 4 decimal positions in an IP address.

NETWORK ADDRESSING.

All communication adapters are encoded with a unique address at the time of manufacture. Each manufacturer is assigned a range of addresses. This is commonly referred to as the Media Access Control (MAC) address and is 6 bytes long. (4 bits = 1 byte).

In order to participate on a network such as the IP network, each node must be assigned a unique Internet Protocol (IP) address which consists of 16 bytes divided into 4 byte positions known as octals. Each octal position is equal to one of the 4 decimal positions in an IP address.

The dominant method for disk and tape access by the server has been the SCSI bus architecture.

SCSI Bus Issues

Skew Limited Distance.

Termination is Mandatory

Host Internal Bus Congestion

Network Attached Storage.Network Attached Storage.

The NAS approachsolved many of the parallel SCSI bus

limitations, but also added a few kinks ofit’s own that proved to be undesirable

for transport of block level storage data.

The NAS approachsolved many of the parallel SCSI bus

limitations, but also added a few kinks ofit’s own that proved to be undesirable

for transport of block level storage data.

Back End Networking.

Module 2Summary.

Module 3

Fibre Channel Protocol

Objectives:

At the end of this module, the student will be able to:

1. Discuss the multiple layers of the FC Protocol.

2. Discuss the physical components of Fibre Channel.

3. Discuss bit stream conversion.

4. Discuss Fibre Channel Ordered Sets.

5. Discuss Fibre Channel data frame structure.

6. Fibre Channel classes of service.

7. Fibre Channel flow control.

8. Fibre Channel addressing.

FC-0 defines and details the physical interface, cables & connectors, transmitters & receivers and their interfaces.

FC-1 defines and details the 8b/10b code and the detection of transmission and reception errors.

FC-2 is the most complex layer. It provides the different classes of service, packetization, exchange & sequencing determination, error detection, segmentation & re-assembly of transmitted data, log-in services for coordinating communication between ports with different capabilities and B to B & E to E flow control.

FC-3 This level is not yet implemented.

FC-4 defines and details the mapping of Fibre Channel capabilities to pre-existing Upper Level Protocols, such as IP, or SCSI.

Cables.

Gigabaud Link Module

Gigabit Interface Converter

BIT STREAM CONVERSION.

All information is encoded 8 bits at a time into two possible 10 bit “Transmission Characters”. One is negative and the other is positive.

The 10 bit character with more 1’s than 0’s is said to have positive disparity. You can guess then, what negative and neutral disparity represent.

The transmission sequence is forced from a positive to negative transition to enable the detection of the end of one bit and the beginning of another.

Running disparity keeps track of the previous transmission event and if it was positive, it sends the negative version next thus maintaining balance on the line.

8 Bits

8B/10B Encoder

Positive

Negative

2 Ten Bit Transmission Characters

Running disparity keeps track of the previous transmission event and if it was positive, it sends the negative version next thus maintaining balance on the line.

ORDERED SETS.

DATA FRAME STRUCTURE

The Start of Frame (SOF)Frame header.Payload.The Cyclical Redundancy Check (CRC)The End of Frame (EOF)

The Fibre Channel standards allow for 65536 frames per Sequence. To put this in perspective as a comparison between IP and Fibre channel, remember that an IP packets total size is equal to 1518 bytes and that a Fibre Channel Sequence is equal to an IP packet from a CPU’s perspective. Do the math and you’ll see why Fibre Channel is optimized for large block data transfers typical of storage data.

CLASSES OF SERVICE.

Class 1 - Dedicated Connection

Class 1 is a service which provides Dedicated Connections. A Class 1 Connection is requested by an N_Port with another N_Port. An acknowledgment (ACK) is returned by the other N_Port to establish the Connection. In general, once a Connection is established, it shall be retained and guaranteed by the Fabric, until one of these N_Ports requests removal of the Connection.

Class 2 - Multiplex

This operating environment provides Connectionless service with notification of non-delivery, (BSY or RJT), between two N_Ports. This service allows one N_Port to transmit consecutive frames to multiple destinations without establishing a Dedicated Connection with any specific N_Port. Conversely, this service also allows one N_Port to receive consecutive frames from one or more N_Ports without having established Dedicated Connections with any of them.

Class 3 – Data gram

This operating environment provides Connectionless service without any notification of non-delivery (BSY or RJT), delivery (ACK), or end-to-end flow control between two N_Ports. The Fabric, if present, and the destination N_Port are allowed to discard Class 3 frames without any notification to the transmitting N_Port. This service allows one N_Port to transmit consecutive frames to multiple destinations without establishing a Dedicated Connection with any specific N_Port. Conversely, this service also allows one N_Port to receive consecutive frames from one or more N_Ports without having established Dedicated Connections with any of them.

FLOW CONTROL.

ADDRESSING.

Each node has a 64 bit Node_Name assigned at the time of manufacture.

Referred to as the World Wide Name and is globally unique.

As with IP, Fibre Channel assigns an address to the port of each node when the port performs a “Log-In” to it’s respective topology. This is a 24 bit address called an N_Port ID and, like an IP address, the N_Port ID is used to route frames within a SAN. 24 bits may not seem like many addresses however, it is equal to 2 to the 24th power (over 16 million addresses).

Chapter 3 Summary.

MODULE 4 - SAN TOPOLOGY

Objectives:

1. Understand and discuss the Point to Point Topology.

2. Understand and discuss the Arbitrated Loop Topology.

3. Understand and discuss the Switched Fabric Topology.

Fibre Channel Ports.

N-Ports

F-Ports

NL- Ports

FL-Ports

E-Ports

G-Ports

Port Login.

3 Methods to Choose From

Fabric Login.

N_Port to N_Port Login.

Loop Login.

Fabric Login.

Whenever an N_Port connects to an F_Port, after power up, the N_Port signals the Fabric.

The Fabric responds.

The N_Port transmits it’s WWN (FLOGI).

Fabric records the N_Port WWN into its Name Server table.

Now the two ports establish a connection performing a Port Login (PLOGI).

The N_Port queries the Fabric Name Server.

The Fabric Name Server send a copy of its WWN/Fabric address table to the N_Port.

The N_Port now performs a PLOGI with the other ports in the Fabric.

Process Login (PRLI) with the other Fabric ports.

N_Port to N_Port Login.

The OLS & LRR are sent and the LR is received.

The N_Port sends the FLOGI.

The port with the lowest WWN waits for a PLOGI from the other N_Port.

The N_Port with the highest WWN sends S_ID & D_ID values in the PLOGI frame.

Loop Login.

Loop Initialization Process.

Loop Initialization Select Master

Loop Initialization Fabric Assigned.

Loop Initialization Previously Assigned

Loop Initialization Hard Assigned

Loop Initialization Soft Assigned

Clarify One Thing

POINT TO POINT TOPOLOGY.

ARBITRATED LOOP TOPOLOGY.

SWITCHED FABRIC TOPOLOGY

Module 4 SUMMARY.

MODULE 5 SAN HARDWARE PRODUCTS

Objectives:

1. Identify and discuss the Fibre Channel Host Bus Adapter (HBA).

2. Identify and discuss Fibre Channel Raid Controllers.

3. Identify and discuss Fibre Channel JBOD (Just a Bunch of Disk).

4. Identify and discuss Fibre Channel Hubs.

5. Identify and discuss the Fibre Channel SCSI to Fibre Bridge (Router).

6. Identify and discuss the Fibre Channel Fabric (Switches).

HOST BUS ADAPTERS.

RAID CONTROLLERS

FIBRE JBOD.

SCSI TO FIBRE BRIDGES (ROUTERS).

FABRICS (SWITCHES)

Module 5 Summary.

REFERENCE MATERIAL

SAN_Basics.ppt

Documents