Chapter1-Basic Storage Technology

8/7/2019 Chapter1-Basic Storage Technology

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1Patni Internal 1


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Copyright 2006 by Patni

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Storage Technology PrimerStorage Technology Primer


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Coverage

Need for Storage & Growth of Data

Why Network Storage?

Storage Performance and Data Protection DAS, NAS, CAS, SAN

Connectivity Technology

Standards Organization


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Need for Storage


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Copyright 2006 by Patni 5

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Growth of Data

020

40

60

80

100

120

140

160

180

200

Exabyte

s*

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

*Exabyte = One Billion Gigabytes

World Wide Production of Information


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Volatile Storage A storage device in which the

contents are lost when power is removed.

Cache Memory -As the microprocessor processes

data, it looks first in the cache memory and if it

finds the data there (from a previous reading of

data), it does not have to do the more time-

consuming reading of data from larger memory. Disk Cache - A disk cache is a mechanism for

improving the time it takes to read from or write

to a hard disk

Volatile Storage


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Non Volatile Storage

MagneticMagnetic OpticalOptical

TapeTape

Mammo h AIT

DLT

LTO

CD

DVD

DiskDisk

ATA Drive

SCSI Drive

Zip Disk

US Disk

ICIC

FFD

SD

MMC


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Storage Issues


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Copyright 2006 by Patni 9 9

Storage Issues


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Evolution of Storage Management

80s70s Late 90s

Host Centric Client/Server NetworkComputing

Enterprise storage Management


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Types of Network Storage

Direct-attached storage (DAS)Storage devices connected to a server

Network-attached storage (NAS)

Storage devices can be accessed over a computer network

Storage area network (SAN)

Storage devices can be accessed through Fibre Channel

Content Addressable Storage (CAS)

Data stored on multiple intelligent nodes

NAS

IPLAN/WAN

SAN

FibreCha erIP LAN

DAS CAS

IP


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DAS Direc AttachedStorage

Storage hardware that connects to a single

server. Also called: Direct Attached

Storage (DAS). DAS is Local storage and

one-to-one relationship.

Most of storage (about 70%) is connected

via DAS today, but 60% of storage will be

connected via SAN by 2007(IDC)


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DAS (contd)

Advantages

Low capital expense,industry-standard parts

Simple straight forwardsetup

Can run applications andperform as a file server

Relative high-performanceat low-cost within a givenDAS island

Disadvantages

The least flexible of all datasharing topologies

Less thanN

AS file servingperformance

Large administrative effort andhigh cost to maintain

Minimal data sharing


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Network Storage Evolution

Se rver

c

ien ts

Disk drives Server

Disk drives

LAN

DASDAS

NASNAS

SANSAN


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Released in 2002 by EMC

Refers to storage of fixed content, that is data

written once and never changed or cant be

altered in any way. Storage schema was designed specifically for

keeping fixed content secure and in place was

inevitable.

CAS provides a digital fingerprint for a stored

piece of data. Also known as an ID or logical

address.

Content Addressed Storage


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Guaranteed integrity and authenticity of information

Location independent & Long-term retention

Continuous online and available

Automatic distribution across devices

Operation and management of information should be

automated

Singapore context

MAS rule that financial documents must be retained for 6

years Companies Act, all financial records must be maintained

for 7 yearsTelecom need to keep their CDRs for 3 years

Requirement of CAS


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How CAS can Impact Business

Confront the increasingly stringent business and legal

requirements to store information for decades.

Storage ecosystem that can alleviate one of today's growing

storage challenge.

Its core software can manage over decades, extraordinary

amounts of fixed content and to integrate easily with

Independent software vendor applications.

Modification of existing applications via its application

programming interfaces.


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Uses a claim check to address objects.

FCS generates a globally unique identifier (claim

check) to later retrieve the object. The client

presents a token and the server replies with the

object.

The token is a set of ASCII characters. Maybe fixed

in length or varies. Token is a unique string

associated with each object in the system.

How does CAS Work?


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SAN, NAS & CASSAN, NAS & CAS-- C par isonComparison

SAN NAS CAS

Block File Object

High

Performance Mixed

Performance/Capacity

High

Capacity


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RAID

What is RAID?

Stands for Redundant Array of Independent Disks.

Developed to meet the growing demands for data reliability andperformance.

Multiple hard drives are grouped together to form a singlelogical drive.

Why RAID?

Mass storage is successful only with the benefits of this

data protecting scheme. Increases the performance and reliability of data storage

by spreading data across multiple disks.


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RAID Concepts

RAID uses Mirroring, Parity and Striping.

Mirroring

Increases fault tolerance by having two copies of the same data on

separate hard drives.

Downtime is minimal and data recovery is simple.

Increased cost and twice as much as storage.

RAID

Controller

A B C

A B C

Disk1

Disk2

Data(ABC)


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RAID

Controller

A C E

B D F

Disk1

Disk2

Data(ABC DEF)

Striping

Improves performance by distributing data across all drives.

The transfer rates for read and write operations are greatly

increased.

There are two levels of striping:

Byte level striping: breaking up of data into bytes.

Block level striping:breaking up of data into specific block sizes.

RAID Concepts (contd)


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RAID Concepts (contd)

Parity

Data redundancy technique used in RAID.

Parity data is created using the logical operation

called XOR on the data elements.If any of the data elements is lost, it is recreated

from the parity element and vice versa.

As in mirroring there is no need to keep two copies

of data.The parity can be either distributed across the

multiple disks or be dedicated to a single disk.


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RAID Levels

Combinations of mirroring, parity and striping results in

various raid levels.Commonly a op e RAID Levels

RAID 0 Striping (no parity)

RAID 1 Disk mirroring

RAID 0+1 Striping, each stripe then mirrored

RAID 2 Bit-level Striping, ECC Disk

RAID 3 Byte-level Striping, fixed parity

RAID 4 Block-level Striping, fixed parity RAID 5 Striping, distributed parity

RAID 6 is two parity over all drives, Handles twodisk failures.Handles twodisk failures.


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RAID 0: Striping

Implements a striped disk array, the data is broken into

blocks each block written to separate disk drive

Not fault-tolerant not a true RAID

Lowercost & higher access rate

Applications in Image Editing & Video Production

Block7

Block5

Block3

Block1

Block8

Block6

Block4

Block2

Disk1 Disk2


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RAID 1 : Mirroring

Consists exactly 2disk modules bound together as mirrored pair.

Controller must perform 2concurrent Reads or2duplicate

Writes, per mirrored pair.

Ifbothdisks fail, the RAID 1 mirrored pairbecomes inaccessible

Recommended Application-Accounting & Payroll.

Block4

Block3

Block2Block1

Block4

Block3

Block2Block1

Disk1 Disk2


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RAID 0/1 : Striping & Mirroring

Even number of 4-16 disk modules

Half are data disks and the other half are disk mirrors

Uses block striping for performance & mirroring for redundancy

- so mirrored RAID 0 group

Block7

Block5

Block3

Block1

Block8

Block6

Block4

Block2

Block7

Block5

Block3

Block1

Block8

Block6

Block4

Block2


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Uses bit level striping with dedicated Error Correction Code (ECC).

Use multiple drive dedicated ECC disks.

Need high number of drivers for ECC generation.

Block4

Block3

Block2

Block1

Block4a

Block3a

Block2a

Block1a

Block4b

Block3b

Block2b

Block1b

ECC

ECC

ECC

ECC

ECC

ECC

ECC

ECC

RAID 2 : Bit-level Striping, Fixed parity


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RAID 3 : Byte-level Striping, Fixed parity

Uses byte level striping with dedicated parity

An additional drive dedicated to parity

Uses Error Correction Code to detect errors

Added parity slow down writes

Block4

Block3

Block2

Block1

Block4a

Block3a

Block2a

Block1a

Block4b

Block3b

Block2b

Block1b

parity

parity

parity

parity


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RAID 4 : Block-level Striping,Fixed parity

Uses block level striping with dedicated parity

Multi user read, single user writes .

Uses Error Correction Code (ECC) to detect error.

Added parity slow down writes.

Block10

Block7

Block4

Block1

Block11

Block8

Block5

Block2

Block12

Block9

Block6

Block3

parity4

parity3

parity2

parity1


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Uses block level striping with distributed parity

Data transferred to disk by independent read and write

operations

Combination of redundancy, cost effectiveness and storage

efficiency

Good for multitasking environment.

parity

Block1b

Block1a

Block1

Block2b

parity

Block2a

Block2

Block3b

Block3a

parity

Block3

Block4b

Block4a

Block4

parity

RAID 5 Striping and Distributed

Parity


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Solutions for Connectivity

Fibre Channel

iSCSI (Internet Small Computer System Interface)

FCIP (Fibre Channel Over Internet Protocol)

iFCP ( Internet Fibre Channel Protocol )


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Introduction to Fibre Channel

High Speed: 2 Gbps, full duplex dedicated

connection.

Provides a general hardware transport vehicle for

Upper Level Protocols (e.g. SCSI, IP, etc)

Reduced congestion

Long Distance: Up to 10km.

Heterogeneous systems support


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Fibre Channel Architecture

ATM

FC - ATM

IP

FC Link

Encapsulation

FC - LE

ULP (Upper Level Protocol) SCSI-3

SCSI - 3 Command

Set MappingFC-4

IPI - 3 Command

Set Mapping

(IPI-3 STD)

FC-3 Common Services

FC-

FC-1

FC-2Fibre Channel Physical

& Signaling Interface

( FC- PH, FC-PH2,

FC-PH3 )Physical Variant

Encode / Decode

Framing ProtocolFC - AL

8B/10B Encoding

Copper, Optical

FC - AL -2


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The Fibre Channel Network

Topology

SCSI Target Node

SCSI Initiator Node

Link

IP Node

Name=1000.3210IP NodeName=1230.3210

Server

StorageSubsystem

SCSI CommandProtocol


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Only 2devicesDirect Connect

Up to126devices

FC Hubs

Up to16 milliondevices

FC switches

Switche FabricArbitrate LoopPoint To Point

Fibre Channel Topologies


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Fibre Channel Node and Port

Node Name=1000ABCD

Nodes

Node Name=6000..1254

N_Port

#1

N_Port

#2

N_Port#3

NL_Port#4

U_Port U_Port

NL_Port

#7

NL_Port

#8

Node

PortName=21008765

N_Port_ID = 123456Each Port hasseparate Transmit andReceive functions

Node: Any device or entity that can initiate and receive transmissionsin a fibre channel network.Eg. Storage device

Port: A fibre Channel port is an intelligent physical hardware thatconnects all components to the network.

Switch and hubs are not considered as nodes as they do not initiate

any transmissions.

A node can have multiple ports


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Fibre Channel Addressing

Each Node has a unique Node_Name ( 64-bit WWNN)assigned by the manufacturer.

As in LAN MAC address, WWN not used for transportation offrames across the network.

Each Node has one or more ports called N_Port (NL_Port)

Each N_Port has a 64-bit Port Name and a 24-bit port addressor N_Port_ID

The 24-bit address is assigned dynamically and optimizesframe routing.

64 bit Node_Name orWWN

Node Port orN_Port64 bit Port Name

24 bitN_Port_ID orport address

Multi-ported Node


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Fibre Channel Port Types

Switch Ports

E _Port = Expansion Port

F _Port = Fabric Port

FL_Port = Fabric Loop Port

G _Port = Generic Port Can Operate as E, F or FL

Device Ports

N _Port = Direct Fabric Attached Device

NL_Port = Loop Attached Device


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Port Visualization

N-Port Node

N-PortNode F-Port F-Port

E-Port

E-Port

FL-Port

G-Port

NL-Port

NL-Port

Switch 1

Switch 2

Fabric

Brocade


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Classes of Service

High speed and Flexible architecture of Fibre Channel enablesit to carry out different applications.eg tape-backup, real-time

video etc.

Different applications have their own delivery requirements

like

bandwidth, connectivity etc.

Fibre Channel defines 5 classes of service that address

different delivery requirements

Class 1- Acknowledged Connection Oriented Service

Class 2- Acknowledged Connection-less Service

Class 3 - Unacknowledged Connection-less Service

Class 4 Fraction Bandwidth Connection Oriented ServiceClass 6 Multicast Service.


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Thanks


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Class 1 Service

N_Port

# 1

N_Port

#2

N_Port

#3

N_Port

#4

Fabric

Connection-Oriented Class of Service. Allows full-bandwidth between a pair of nodes with a

confirmation of delivery and End To End Flow Control

In-Order delivery of frames due to dedicated connection.

Best suited for real-time applications like video processing.

Connections are established and removed at sequence boundaries.


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Class 2 Service

N_Port

#2

N_Port

#1Frame 1:5

N_Port

#5

N_Port

#2

Frame 1:5

Frame 2:1

Frame 2:2

Connection-less service class and no bandwidth is reserved.

Frames are routed by the fabric using internal routing algorithms.

Do not guarantee In-Order delivery of frames, but there is

confirmation of delivery.


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Class 3 Service

It is a connection-less and unacknowledged service.

Frame routing done internally by the fabric.

Also known as the datagram service, as it is the quickesttransmission without involving the acknowledgement.

If a frame cannot be processed then, it is discarded withoutnotification.

First frame of sequence

Data Frame

Last data frameFirst frame of sequence

Data Frame

Last data frame

Sequence

Initiator

Sequence

Recipient

Sequence

Initiator

Sequence

Recipient


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Class 4 Service

This service is connection-oriented providing a virtual circuitbetween a pair of nodes.

Known as Fractional Bandwidth, as it assigns only a fraction ofthe total bandwidth and different QoS parameters for each

connection.

The QoS parameters for each services ensures that certain time-

critical applications always have bandwidth available.

Exists only as a standard due to its complexity.


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Class 6 Service

Initiator

N_Port

Multicast

server

N_Port

N_port

N_Port

RecipientFabricConnectrequest

ACK

ACKs

from the

targets

Provides reliable multicast service with acknowledged delivery. It is only a variation from Class1 service in a way the responsesare processed by recipients of the multicast group.

A multicast server serves consolidates all acknowledgements,thereby returning only a single confirmation to the initiator.

Example, A video broadcast application, with a central videoserver and multiple video recipients.

Chapter1-Basic Storage Technology

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