Hard Disk Storage

A hard disk drive contains rigid, disk-shaped platters, usually constructed of aluminum or glass

Also known as a Fixed DiskGrown rapidly in size and

performance and have dropped dramatically in price over recent years

Hard Disk Drive Operation

consists of spinning disks with heads that move over the disks and store data in tracks and sectors

heads read and write data in concentric rings called tracks, which are divided up into segments called sectors

Hard Drive Anatomy

Disk platters

Logic board

Read/write heads and Spindle motor

Cables and connectors

Head actuator mechanism

Configuration items (such as jumpers or switches)

S.M.A.R.T

Stands for Self-Monitoring, Analysis and Reporting Technology

Industry standard providing failure prediction for disk drives

According to Seagate, 60% of drive failures are mechanical, which are exactly the type of failures S.M.A.R.T. is designed to predict.

Caching

Has a major effect on disk drive performance

Can be software (Smartdrv in DOS or Vcache in Windows)

Can be hardware Many IDE and SCSI drives have

cache memory built directly into the drive’s on-board controller

The IDE Interface

A generic term applied to any drive with an integrated (built-in) disk controller

The IDE interface as we know it is officially called ATA (AT Attachment) and is an ANSI standard

Placing the controller on the drive gives IDE drives an inherent reliability advantage over interfaces with separate controllers

IDE Controllers

Many people who use systems with IDE connectors on the motherboard believe that a hard disk controller is built into their motherboard. It’s actually part of the drive

The IDE connector on motherboards in many systems is nothing more than a stripped-down bus slot

IDE Bus Versions

XT IDE (8-bit ISA) AT Attachment (ATA) IDE (16-bit

ISA)MCA IDE (16-bit Micro ChannelOnly the ATA version is used today

ATA Standards

ATA-1ATA-2 ATA-3ATA-4 (ATAPI)ATA-5 (ATAPI)

The SCSI Interface

Stands for Small Computer System Interface

General purpose interface used for connecting many types of devices to a PC

Many PC manufacturers have standardized SCSI for high-end systems (fast, up to 160Mb per second!)

SCSI Standards

Standard SCSIFast SCSIFast-20(Ultra)Fast-40(Ultra2)Fast-80(Ultra3)

Termination

Improper termination still is one of the most common problems in SCSI installations

Three popular types of termination Passive

Active (also called Alternative 2)

Forced Perfect Termination

SCSI Drive Configuration

More complicated than IDE drivesNeed to set SCSI ID setting and

Terminate any open resistors Most SCSI host adapters are factory-

set to ID 7 or 15

Setting the ID usually involves changing jumpers on the drive

SCSI Versus IDE

IDE drives usually cost less than SCSI drives (popular for home or budget PCs)

SCSI allows for smoother multitasking and increased overall data throughput (popular for high end workstations or servers