Introduction to Hard Introduction to Hard DrivesDrives

Chapter 6 - Key Terms Chapter 6 - Key Terms

Information Compiled by Diane Ferris, Michele Henderson & Vicki Kertz

Hard Drive TechnologiesHard Drive Technologies

IDE

EIDE

SCSI

Integrated Device Electronics

Enhanced Integrated Device Electronics

Small Computer Systems Interface

IDE DrivesIDE Drives

Hard drive whose disk controller is Hard drive whose disk controller is integrated into the drive, eliminating the integrated into the drive, eliminating the need for a controller cable and thus need for a controller cable and thus increasing speed, as well as reducing increasing speed, as well as reducing price.price.

Uses an IDE 40-pin data cable and 4-pin Uses an IDE 40-pin data cable and 4-pin power cable.power cable.

EIDE DrivesEIDE Drives

Newer drive standard that allows systems Newer drive standard that allows systems to recognize drives larger than 504 MB to recognize drives larger than 504 MB and to handle up to four devices on the and to handle up to four devices on the same controller.same controller.

SCSI TechnologySCSI Technology

Faster system-level interface with a host adapter and a bus that can daisy chain as many as seven or 15 other devices.

SCSI TermsSCSI Terms

SCSI ID

SBAC

Embedded SCSI

Terminating Resistor

Termination

A number from 0 to 15 assigned to each SCSI A number from 0 to 15 assigned to each SCSI device attached to a daisy chain.device attached to a daisy chain.

SCSI Bus Adapter Chip The chip mounted on the logic board of a hard drive that allows the drive to be a part of a SCSI bus system.

Devices that contain their own host adapter, with the SCSI interface built into the device.

The resistor added at the end of a SCSI chain to dampen the voltage at the end of the chain.

A process necessary to prevent an echo effect of power at the end of a SCSI chain resulting in interference with the data transmission.

SCSI Device DriversSCSI Device Drivers

ASPI

CAM

Advanced SCSI Programming Interface – A popular device driver that enables operating systems to communicate with a SCSI host adapter. (The “A” originally stood for Adaptec.)

Common Access Method – A standard adapter driver used by SCSI

Types of FormattingTypes of Formatting

Low-level formatLow-level format

High-level formatHigh-level format

A process (usually performed at the A process (usually performed at the factory) that electronically creates factory) that electronically creates the hard drive cylinders and tests for the hard drive cylinders and tests for bad spots on the disk surface.bad spots on the disk surface.

Format performed by the OS that Format performed by the OS that writes a file system to a logical drive. writes a file system to a logical drive. For DOS and Windows 9x, the For DOS and Windows 9x, the command used is FORMAT, which command used is FORMAT, which writes a FAT and a directory to the writes a FAT and a directory to the drive. Also called drive. Also called OS formatOS format..

Hard Drive PartitionsHard Drive Partitions

PartitionPartition

Partition tablePartition table

MBRMBR

Logical DriveLogical Drive

A division of a hard drive that can be used to A division of a hard drive that can be used to hold logical drives.hold logical drives.

A table at the beginning of the hard drive that A table at the beginning of the hard drive that contains information about each partition on contains information about each partition on the drive.the drive.

The first sector on a hard drive, which The first sector on a hard drive, which contains the partition table and other contains the partition table and other information needed by BIOS to access the information needed by BIOS to access the drive.drive.

A portion or all of a hard drive partition that is A portion or all of a hard drive partition that is treated by the operating system as though it treated by the operating system as though it were a physical drive containing a boot were a physical drive containing a boot record, FAT and root directory.record, FAT and root directory.

CHSCHS

ECHSECHS

LBALBA

The traditional method where BIOS reads and writes to The traditional method where BIOS reads and writes to hard drives by addressing the correct cylinder, head and hard drives by addressing the correct cylinder, head and sector (CHS). Also called sector (CHS). Also called normal modenormal mode..

Extended CHS - Addresses information on hard drives Extended CHS - Addresses information on hard drives ranging from 504 MB to 8.4 GB, by translating CHS ranging from 504 MB to 8.4 GB, by translating CHS information in order to break the 528 MB HD barrier. Also information in order to break the 528 MB HD barrier. Also called called large modelarge mode..

Logical Block Addressing – Where the BIOS and OS view Logical Block Addressing – Where the BIOS and OS view the drive as one long linear list of LBAs or addressable the drive as one long linear list of LBAs or addressable sectors, permitting drives to be larger than 8.4 GB. sectors, permitting drives to be larger than 8.4 GB.

ModesModes

TranslationTranslation

Physical Physical GeometryGeometry

Logical GeometryLogical Geometry

Enhanced BIOSEnhanced BIOS

A technique used by system BIOS and HD A technique used by system BIOS and HD controller BIOS to break the 504 MB HD barrier. controller BIOS to break the 504 MB HD barrier. This allows a different set of drive perimeters to This allows a different set of drive perimeters to communicate to the OS and other software than communicate to the OS and other software than that used by the hard drive controller BIOS.that used by the hard drive controller BIOS.

Actual layout of heads, tracks, and sectors on a Actual layout of heads, tracks, and sectors on a hard drive.hard drive.

The number of heads, tracks, and sectors that the The number of heads, tracks, and sectors that the BIOS on the hard drive controller presents to the BIOS on the hard drive controller presents to the system BIOS and the OS. Doesn’t consist of the system BIOS and the OS. Doesn’t consist of the same values as the physical geometry.same values as the physical geometry.

A newer BIOS that has been written to A newer BIOS that has been written to accommodate larger-capacity gigabyte drives.accommodate larger-capacity gigabyte drives.

Mode TermsMode Terms

DOS CommandsDOS CommandsMKDIRMKDIR

CHDIRCHDIR

RMDIRRMDIR

TREETREE

ATTRIBATTRIB

MIRRORMIRROR

UNFORMATUNFORMAT

Used to create a directory on a driveUsed to create a directory on a drive

Changes the current default directory.Changes the current default directory.

Used to remove an unwanted directory. You Used to remove an unwanted directory. You must delete all files in the directory prior to must delete all files in the directory prior to using.using.

Shows the disk directories in a graphical Shows the disk directories in a graphical layout.layout.

Displays or changes the read-only, archive, Displays or changes the read-only, archive, system and hidden attributes to files.system and hidden attributes to files.

Saves partition table info to disk when used Saves partition table info to disk when used with /PARTN parameter.with /PARTN parameter.

Reverses the effect of accidental formats and Reverses the effect of accidental formats and repairs a damaged partition table if it was repairs a damaged partition table if it was saved with MIRROR /PARTN command.saved with MIRROR /PARTN command.

Fragmentation and ClustersFragmentation and Clusters

FragmentationFragmentation

DefragmentDefragment

Cross-Linked ClustersCross-Linked Clusters

Lost ClustersLost Clusters

CHKDSK /FCHKDSK /F

Distribution of data files, such that Distribution of data files, such that they are stored in noncontiguous they are stored in noncontiguous clusters.clusters.

To “optimize” or rewrite a file to a To “optimize” or rewrite a file to a disk in one contiguous chain of disk in one contiguous chain of clusters, thus speeding up data clusters, thus speeding up data retrieval.retrieval.

Errors caused when files appear to Errors caused when files appear to share the same disk space, share the same disk space, according to the FAT.according to the FAT.

Lost file fragments that, according to Lost file fragments that, according to the FAT, contain data that does not the FAT, contain data that does not belong to any file.belong to any file.

CHKDSK /F can free lost file CHKDSK /F can free lost file fragments.fragments.

CompressionCompression

Disk CompressionDisk Compression

Data CompressionData Compression

Compressed DriveCompressed Drive

CVFCVF

Drive SpaceDrive Space

Compressing data on a hard drive to allow Compressing data on a hard drive to allow more data to be written to the drive.more data to be written to the drive.

Reducing the size of files by various Reducing the size of files by various techniques such as using a shortcut code to techniques such as using a shortcut code to represent the repeated data.represent the repeated data.

A drive whose format has been reorganized to A drive whose format has been reorganized to store more data; not a drive, but a type of file, store more data; not a drive, but a type of file, typically with a host drive called H.typically with a host drive called H.

Compressed Volume File – File on the host Compressed Volume File – File on the host drive of a compressed drive that holds all drive of a compressed drive that holds all compressed data.compressed data.

A utility that compresses files so that they take A utility that compresses files so that they take up less space on a disk drive, creating a single up less space on a disk drive, creating a single large file on the disk to hold all the large file on the disk to hold all the compressed files.compressed files.

Disk CachingDisk Caching

SMARTDriveSMARTDrive

VCACHEVCACHE

A hard drive Cache program that comes A hard drive Cache program that comes with Win 3.x and DOS that can be with Win 3.x and DOS that can be executed as a TSR from the executed as a TSR from the AUTOEXEC.BAT file.AUTOEXEC.BAT file.

A built-in Win 9x 32-bit software cache A built-in Win 9x 32-bit software cache that doesn’t take up conventional that doesn’t take up conventional memory space or upper memory space, memory space or upper memory space, as SMARTDrive does.as SMARTDrive does.

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