SAN Foundations

7/28/2019 SAN Foundations

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Aug 2005

Scalability of inbuilt storage is limited to the servers

predetermined capacity and cannot be shared.

Extending the storage with scsi is Limited to 15

devices


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Aug 2005

Storage Area Networks (SAN) offer a powerful solution for consolidating

storage resources to boost storage management, flexibility, and cost

effectiveness.


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Direct Attached Storage (Internal)

Computer System

CPU

Memory

Bus

I/O - RAID

Controller

Disk Drives


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Computer System

CPU

Memory

Bus

I/O - RAID

Controller

Disk Drives

12345

Data


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Computer System

CPU

Memory

Bus

I/O - RAID

Controller

Disk Drives

12345


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DAS w/ internal controller and external

storage

CPU

Memory

Bus

I/O - RAID

Controller

Computer System

Disk Drives

Disk Drives

Disk Drives

Disk Enclosure

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Comparing Internal and External Storage

Internal Storage

Server

Storage

RAID controllers

and disk drives

are internal to the

server

SCSI, ATA, orSATA protocol

between controller

and disks

SCSI Bus w/ external storage

Server

RAID Controller

Storage

RAID Controller

Disk Drives

RAID controller is

internal

SCSI or SATA

protocol between

controller and

disks

Disk drives areexternal

Disk Drives


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DAS w/ external controller and external

storageComputer System

CPU

Memory

Bus

HBA

RAID

Controller

Storage System

Disk Drives

Disk Drives

Disk Drives

Disk Enclosure12345


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DAS over Fibre Channel

Server

HBA

Storage

Disk drives and

RAID controllerare external

Disk Drives

RAID Controller

HBA is internal

Fibre Channel

protocol

between HBAsand external

RAID controller

External SAN Array


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I/O Transfer

RAID Controller Contains the smarts

Determines how the data will be written (striping, mirroring, RAID10, RAID 5, etc.)

Host Bus Adapter (HBA)

Simply transfers the data to the RAID controller. Doesnt do any RAID or striping calculations.

Dumb for speed.

Required for external storage.


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The most familiar form of storage.

This offers high performance. Runs on various versions of SCSI and newer

standards like eSATA

Access Devices like Hard disks, tape drives

& Robotic controls in a Tape library

Now expanding to USB based connections


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NAS Network Attached Storage

File-oriented access

Multiple Clients, Shared Access to Data

SAN Storage Area Network

Block-oriented access

Exclusive Access to Data


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High-speed network that allows the establishment of direct

connections between storage devices and processors (servers)

within the distance supported by Fibre Channel.


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Aug 2005

NAS and SAN

NAS Network Attached Storage

File-oriented access

Multiple Clients, Shared Access to Data

SAN Storage Area Network

Block-oriented access

Single Server, Exclusive Access to Data


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Aug 2005

High-speed network that allows the establishment of

direct connections between storage devices and

processors (servers) within the distance supportedby Fibre Channel.


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Aug 2005

Facilitates direct, high speed data transfers

Server to storage

Server to server

Storage to storage


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Aug 2005

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.


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Aug 2005

LUNShort forlogicalunit

number

A unique identifier used on a SCSI bus to

distinguish between devices that share the

same bus

Address for individual disk
http://63.236.18.118/RealMedia/ads/click_nx.ads/intm/sbc/www.webopedia.com@468x60-1,468x60-2,125x125-1,336x280,125x800,cp1,cp2,cp3,cp4,cp5,cp6,cp7!accessunit


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Aug 2005

Redundant Array of Inexpensive Disks


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Aug 2005

Fibre Channel environment

Physical Logical


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switch

Fibre Channel

Components

Servers

Host Bus Adapters

Cables

Fiber optic or copper Fibre Channel Switches

Two switches for redundancy

Fibre Channel Storage Array

Two RAID Controllers for redundancy

4100+ disk drives per array

A true storage network

Multiple servers Multiple switches

Multiple Storage Arrays

RAID Controller RAID Controller

switch

Server A

HBA

Server B

HBA

Server C

HBA

Disk Drives

FC Storage Array

HBA HBA HBA


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Aug 2005

Physical layers


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Fibre Channel Frame Dissection

Up to 2048 byte

payload

4 byte checksum for

each frame


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Aug 2005

Classes of service

The classes of service are the characteristics and guarantees

of the transport layer of a Fibre Channel circuit

Class 1 Acknowledged Connection Service

Class 2 Acknowledged Connectionless Service

Class 3 Unacknowledged Connectionless Service

Class 4 Fractional Bandwidth Connection Oriented Service

Class 6 Simplex Connection Service


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SCSI vs. Fibre Channel Interface for internal storage to external

disks Potential down time w/ SCSI

Single bus

RAID controller is SCSI hardware

Standards:

Ultra2 (80 MB/sec)

Ultra 160 (160 MB/sec)

Ultra 320 (320 MB/sec)

Media specific (copper only) SCSI Limitations:

Cables cant be any longer than 3feet for single ended; 15 feet forLVD (low voltage differential)

No more than 15 devices on aSCSI bus

# of disk drives

Used with SAN

Lots of built-in redundancy with connections Redundant network

HBA is fibre channel hardware

Standards:

FC1: 100 MB/sec

FC2: 200 MB/sec

Provides a data link layer above the physicalinterconnect

Analogous to Ethernet FC is a network of devices

It can be media independent- copper or fibreoptic

Fibre Channel limitations:

Cable length: Up to 10 kilometers (more alimitation of cable than FC itself)

Up to 127 devices

# of disk drives


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Aug 2005

Topologies

Point-to-pointThe point-to-point topology consists

of a single connection between two nodes. All the

bandwidth is dedicated to these two nodes.

LoopIn the loop topology, the bandwidth is shared

between all the nodes connected to the loop. The loop

can be wired node-to-node; however, if a node fails or

is not powered on, the loop is out of operation. This is

overcome by using a hub. A hub opens the loop when a

new node is connected, and closes it when a node

disconnects.

Switched or fabricA switch allows multipleconcurrent connections between nodes. There can be

two types of switches: circuit switches and frame

switches. Circuit switches establish a dedicated

connection between two nodes, where as frame

switches route frames between nodes and establish the

connection only when needed. This is also known as

switched fabric.


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Aug 2005

SAN components

SAN servers

SAN storage

SAN interconnects

Adapters

Extenders

Hubs

Routers

Gateways

Switches


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Aug 2005

Hardware Components

Fiber-optic cables come in two distinct types: Multi-Mode fiber

(MMF) for short distances (up to 2 km), and Single-Mode Fiber

(SMF) for longer distances (up to 100 km).

Fibre Channel does not necessarily mean just fiber optic cable.

Copper or optical cables.


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Aug 2005

GBICs are small serial-to-serial, hot-swappable modules

used to provide the media interface (copper or fiber)

2Gbit/sec devices use GBIC called a Small Form FactorPlug (SFP)

Short Wave Laser GBIC or SFP Up to 500 meters

Long Wave Laser GBIC or SFP Up to 10 kilometers

Extended Long Wave Laser GBIC -Up to 80kilometers

GBIC


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Aug 2005

HBA (Host Bus Adaptor)

Provides an interface between the server or workstation internalbus (such as PCI or

SBUS) and the Fibre Channel network

HBA software driver provides the storage information required bythe operating

system

Handles I/O and control requests

Copper/Optical media support (may be dual port cards)


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Aug 2005

Extenders

HUB

Gateways

Used to facilitate longer distancesbetween nodes that exceed the

theoretical maximum.

Used in a SAN to attach devices orservers which do not support switched

fabrics, but only FC-AL.

A gateway (also referred to as a bridgeor a router) is a fabric device used to

interconnect one or more storage

devices with different protocol support,

such as SCSI to FC, or FC to SCSI

devices.


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Aug 2005

Switches are among the highest performing devices available for

interconnecting large numbers of devices, increasing bandwidth, reducing

congestion, and providing high aggregate throughput.


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Prepared by: Sudheer Mundoli Subramannian 24th37
http://www.csc.com/


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Aug 2005

What is Fabric ?

Virtual space used by nodes to communicate with

each other.

One switch or group of switch connected together.

Routes traffic between attached devices

Component identifiers

Domain ID

World wide name.


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Aug 2005

Fibre Channel Port Types


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Aug 2005

FibreChannel -

WWPN

World-Wide Port Number

A unique 64-bit hardware address for eachFibreChannel Device

Analogous to a 48-bit ethernet hardware address

WWNN - World-Wide Node Number


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Aug 2005

Fabric ZoningZoning is a method of providing access control in a Fibre Channelfabric consisting of a single Fibre Channel switch or cascadedswitches.

Port Zoning (Soft Zoning) Zoning by a switch'sdomain/port numbers forming the S_ID

WWN Zoning (Hard Zoning) Zoning by a WWN of theattached node. Each Fibre Channel node has two WWNs: a Port WWN(WWPN) and a Node WWN (WWNN). The WWPN is a unique number

assigned to the physical Fibre Channel Port, and is the name to be

used in creating WWN zoning.


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Aug 2005

Port Zoning - Hard Zoning


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Aug 2005

WWN Zoning Soft Zoning


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HP Business Copy

HP Continues Access

Hitachi Shadow Image

Hitachi True Copy

Time Finder (Snap/Clone) SRDF
http://images.google.co.in/imgres?imgurl=http://www.pertlink.net/images/HP%20Logo.jpg&imgrefurl=http://www.pertlink.net/events2003.html&h=955&w=1015&sz=41&tbnid=msFkpZeKpVTPuM:&tbnh=140&tbnw=149&prev=/images?q=hp+logo&start=2&sa=X&oi=images&ct=image&cd=2


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HP Business Copy


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HP Continues Access


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Aug 2005

LUN - Persistent Binding

Persistent Binding of LUNs to Server Device IDs

Permanently assign a System SCSI ID to a LUN.

Ensures the Device ID Remains Consistent AcrossReconfiguration Reboots

Different HBAs use different binding methods & syntax

Tape Drive Device Changes have been a repeated source ofNetBackup Media Server Failure


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Aug 2005

SAN Performance More Spindles are Better

Faster Disks are Better

Common Switch for Server & Storage

Multiple hops reduce performance

Increases Reliability

Large Port-count switches32 ports or more

16 port switches create larger fabrics simply to

carry its own overhead


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Aug 2005

SAN Good Housekeeping

Stay Current With OS Drivers & HBA Firmware

Before You Buy a Servers HBA

Is it supported by the switch & storage vendors?

Coordinate Firmware Upgrades

Storage & Other Server Admin Teams Using SAN

Monitor Disk I/O Statistics

Be Proactive; Identify and Eliminate I/O Problems

Documents

SAN Foundations