Hard Disk Storage  A hard disk drive contains rigid, disk- shaped platters, usually constructed of aluminum or glass §Also known as a Fixed Disk §Grown 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 l Disk platters l Logic board l Read/write heads and Spindle motor l Cables and connectors l Head actuator mechanism l 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 Channel §Only the ATA version is used today

ATA Standards  ATA-1  ATA-2 §ATA-3 §ATA-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 SCSI §Fast SCSI §Fast-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 l Passive l Active (also called Alternative 2) l Forced Perfect Termination

SCSI Drive Configuration §More complicated than IDE drives  Need to set SCSI ID setting and Terminate any open resistors l Most SCSI host adapters are factory-set to ID 7 or 15 l 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