Storage Systems ArchitecturePart1

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Introduction

Section 2 Storage Systems

Architecture


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Section Objectives

Storage Systems Architecture - Introduction- 2

Upon completion of this Section, you will be able to:

Describe the host environment.

Describe common connectivity components and protocols.

Describe features of intelligent disk subsystems. Describe data flow from the host to/from the disk.


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In this Section


This section contains the following modules:

1. The Host Environment

2. Connectivity

3. Physical Disks4. RAID Arrays

5. Storage Systems


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Storage System Environment



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. From the hosts perspective, storage access (read and write)occurs via

Physical components: CPU Memory Bus

Logical components: Software applications Operating system

File systems Databases.


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Parts of a Storage Environment:

Connectivity



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Network Connectivity encompasses everything between the host and the storage system. Physical components of Connectivity include:

Wiring Host internal bus(es)

Cables Optical and Copper

Connectors and plugs

Adapters Host Bus Adapter (HBA)enables devices to connect to a hosts internal bus system.

Network Interface Cardsenables simple network attachments to a host.

Switches/hubs Manage traffic within a network.

Logical components of Connectivity include

Communication protocols

Device Drivers


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Parts of a Storage Environment:

Storage



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Physical components of storage include: Physical devices that hold the data (i.e., disk, tape, optical

drives, etc.)

Components that make the devices operate (i.e., power

supplies, fans) The enclosures that hold the equipment (e.g., racks)

Logical components of storage include:

Protocols

Flow algorithms


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Module 2.1

The Host Environment


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The Host Environment


Upon completion of this module, you will be able to:

List the hardware and software components of the host

environment

Describe key protocols and concepts used by each

component


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Examples of Hosts


LaptopServer

Group of Servers

Mainframe


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Host Physical Components


Bus

I/O Devices

CPU Storage


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CPU


CPU

Bus

BusALU

Registers

L1 Cache


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Storage


0

1

2

3

n

Data 0

Data n

Data 2

Data 3

Data 1

Address Content

Disk

Memory


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Storage Hierarchy Speed and Cost


Speed

Slow

Fast

Cost

HighLow

TapeOptical

disk

Magnetic

diskRAM

L2 cacheL1 cache

CPU registers


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I/O Devices


Human interface Keyboard

Mouse

Monitor

Computer-computer interface

Network Interface Card (NIC)

Computer-peripheral interface

USB (Universal Serial Bus) port Host Bus Adapter (HBA)


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Host Environment: Logical Components


Host

Apps

Volume Management

DBMS Mgmt Utilities

File System

Multi-pathing Software

Device Drivers

HBA HBA HBA

Operating System


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File System: Metadata Examples


UNIX (UFS) File type and permissions

Number of links

Owner and group IDs

Number of bytes in the file Last file access

Last file modification

Windows (NTFS) Time stamp and link count

File name

Access rights

File data Index information

Volume information


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File Systems: Journaling and Logging


Improves data integrity and system restart time over non-journaling file systems.

Uses a separate area called a log or journal.

May hold all data to be written

May hold only metadata

Disadvantage - slower than other file systems.

Each file system update requires at least 1 extra writeto the log


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HBAs


Host

Apps

Volume Management

DBMS Mgmt Utilities

File System

Multi-pathing SoftwareDevice Drivers

HBA HBA HBA

Operating System


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Improving Data Availability at the Host


Redundancy:

Multiple HBAs

Multi-pathing software

Clustering


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How Files are Moved to and from

Storage


Teacher

Configures /

Manages

File System Files

Mapped by file

system to

Course File(s)

Reside

in

File System Blocks

Disk PhysicalExtents

Consisting of

LVM LogicalExtents

Residing inMapped byLVM to

Disk Sectors

Managed by Disk

Storage

Subsystem


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Check Your Knowledge


What are some examples of hosts?

Describe the hardware components found in most hosts.

What is the function of the operating system?

What is the function of the file system? What are some techniques that can be used to improve

availability at the host?

What is volume management?


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Module 2.2

Connectivity


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Connectivity


Upon completion of this module, you will be able to: Describe the physical components of a networked storage

environment.

Describe the logical components (communication protocols)

of a networked storage environment.


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Physical Components Host with

Internal Storage


Bus

Disk

Cable

Host

Port

Port

HBA

CPU


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Bus Technology


Serial

Serial Bi-directional

Parallel


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Bus Technology


System Busconnects CPU to Memory Local (I/O) Buscarries data to/from peripheral devices.

Bus width measured in bits

Bus speed measured in MHz Throughput measured in MB/S


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Connectivity Protocols


Protocol = a defined format for communicationallows thesending and receiving devices to agree on what is being

communicated.

Tightly

ConnectedEntities

Directly

AttachedEntities

Network

ConnectedEntities


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Communication Protocols


Host

Apps

Operating System

PCI

SCSI or IDE/ATA Device Drivers


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Bus Technology - PCI


Peripheral Component Interconnect (PCI) defines the localbus system within a computer

It is an interconnection between microprocessor and attached

devices, in which expansion slots are spaced closely for high-

speed operation.

Has Plug and Play functionality.

PCI is 32/64 bit

Throughput is 133 MB/sec


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IDE/ATA


Integrated Device Electronics (IDE) / Advanced TechnologyAttachment (ATA)

Most popular interface used with modern hard disks

Good performance at low cost

Desktop and laptop systems

Inexpensive storage interconnect


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SCSI - Small Computer System

Interface


Most popular hard disk interface for servers. Higher cost than IDE/ATA.

Supports multiple simultaneous data access.

Currently both parallel and serial forms.

Used primarily in higher end environments.


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SCSI Model


Target

Initiator


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SCSI Model


Target

ID

Initiator

ID

LUNs


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Disk Identifier - Addressing


Host Addressing

Controller

Target

LUN

c0 - Controller

Initiator, HBA

PeripheralController

t0

Target

LUNs

d0 d1 d2

c0 t0 d0


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Comparison IDE/ATA vs SCSI

Stora e S stems Architecture - Introduction - 4

Feature IDE/ATA SCSI

Connectivity Market Internal Storage Internal and External

Storage

Speed (MB/sec) 100/133/150 320

Hot Pluggable No Yes

Expandability Easier to set up Very good but very

expensive to set up

Cost/Performance Good High cost/Fast

transfer speed


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Physical Components Host with

External Storage


Bus

Disk

Cable

Host

Port

Port

HBA

CPU


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Fibre Channel


Fibre Channel

Storage Arrays

HostApps

DBMS Mgmt UtilsFile System

LVM

Multipathing Software

Device Drivers

HBA HBA HBA

E l S I f A


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External Storage Interfaces A

Comparison


SCSI Limited distance

Limited device count

Usually limited to single initiator

Single-ported drives

Fibre Channel

Greater distance

High device count in SANs

Multiple initiators

Dual-ported drives


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Fibre Channel Connectivity


Switches Storage

Hosts


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Module Summary

Storage Systems Architecture - Introduction

Key points covered in this module: The physical components of a networked storage

environment.

The logical components (communication protocols) of a

networked storage environment.

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Storage Systems ArchitecturePart1

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