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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.
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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 • 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 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 • Passive • Active (also called Alternative 2) • Forced Perfect Termination
SCSI Drive Configuration • More complicated than IDE drives • Need 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