7-1 Hard Drive. 7-2 Section Objectives After completing this section you will be able to: Install or replace a floppy drive Define and explain fundamental.

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Hard Drive

7-2

Section Objectives

After completing this section you will be able to: Install or replace a floppy drive Define and explain fundamental hard drive terminology Compare and contrast IDE and SCSI technologies

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Floppy Drive Overview

The floppy drive subsystem consists of three main parts: (1) the electronic circuits or the controller, (2) the 34-pin ribbon cable, and (3) the floppy drive.

The electronic circuits give the floppy drive instructions. The electronic circuits can be built into the motherboard or on

an adapter. The floppy cable connects the floppy drive to the electronic

circuits. The floppy drive allows saving data to disk media.

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Floppy Media

Disk – also called floppy disk – The media inserted in a floppy drive.

Write-Protect Window – A small window in the corner of a floppy with a sliding tab to open or close the window. If the window is open the disk is write-protected.

1.44 MB Disks – 3.5” today’s floppy disks.

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Floppy Media1.44MB with write-Protect and high density windows

Floppy – Figure 7.1

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Floppy Drive Construction

Floppy drives have two read/write heads that place the data onto the disk.

Floppy disks are inserted between the two read/write heads in the floppy drive. The disk turns inside the disk jackets and the floppy drive heads physically touch and scan the disks to read and write data.

Over time, the read/write heads become dirty. When a technician sees read/write errors occurring the first step is to clean the read/write heads.

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Floppy Disk Geometry

• When a disk is formatted concentric circles called tracks are drawn on that disk. 1.44MB disks have 80 tracks.

• Sector – Tracks are further subdivided into pie-shaped wedges. A sector is the section defined between a tract and an intersecting line and holds 512 bytes of information.

• Cluster – The minimum amount of space one file occupies. On a floppy disk a cluster is 1024 bytes or two sectors.

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Floppy Disk GeometryDisk with 80 tracks


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Floppy Disk GeometrySectors and sector numbering


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Floppy Drive Installation

Installation of floppy drives is simple after doing some preliminary homework:

An available drive bay An available power connection A motherboard floppy connector available or install an

additional adapter A floppy cable

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Floppy Connector on Motherboard

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Floppy Drive Configuration

Floppy drive cable


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Pin 1 on the cable attaches to Pin 1 on the connector. Pin 1 is identified by a red stripe on the cable. Most manufacturers identify Pin 1 in writing on the

motherboard. Installing the floppy is mounting the drive to the case

and connecting the cable from the drive to the motherboard or adapter.

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Hard Drive Overview

Hard drives are a popular devices for storing data.

The hard drive subsystem can have up to three parts:– The hard drive– Cables that attach to an adapter or the motherboard– Control circuits located on an adapter or the

motherboard

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Hard Drive Geometry

Components of a Hard Drive:

– Platters are multiple hard metal surfaces contained in the hard drive.

– Read/Write Heads write and read the 1s and 0s to and from the hard drive surface.

Head Crash – When a read/write head touches the hard drive platter.

– Track – Concentric circle on a hard drive platter.

– Cylinder – One corresponding track on all surfaces of a hard drive.

– Sectors – Each track is divided into sectors of 512 bytes.

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Hard Drive GeometryHard Drive Geometry

IDE/SCSI – Figure 7.6

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Hard Drive GeometryCylinder versus tracks


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Hard Drive Interfaces Overview

There are two major hard drive interfaces:

– IDE (integrated drive electronics) – Also known as ATA (AT Attachment) standard. IDE is most common in home/office computers.

– SCSI (small computer system interface) – SCSI is most common in network servers.

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IDE (Integrated Drive Electronics) IDE (Integrated Drive Electronics) is used with hard drives, as well as tape, Zip, CD

and DVD drives.

Two types of IDE

– PATA (Parallel ATA) – Older ATA type. PATA uses a 40-pin cable to connect

the IDE hard drive to the motherboard or an adapter and transfers 16 bits of data

at a time.

– SATA (Serial ATA) – Is a point to point interface in which each device connects

to the host through a dedicated link and has the entire interface bandwidth.

ATA-1 – Original IDE interface standard.

ATA-2 – Faster transfer rates than ATA-1.

DMA mode (direct access mode) – DMA is supported by ATA-2. It allows data

transfer between RAM and the hard drive without going through the CPU.

UDMA (ultra DMA) – Also known as bus master DMA. Latest type of DMA.

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IDE (Integrated Drive Electronics)

IDE PATA Standards

IDE/SCSI – Table 7.2

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SCSI (Small Computer System Interface)

SCSI (Small Computer System Interface) is an interface standard that connects multiple small devices to the same adapter via a SCSI bus.– SCSI bus is the bus shared by all devices that attach

to one SCSI adapter.– Host Adapter connects the SCSI device to the

motherboard and coordinates the activities of other devices connected.

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SCSI (Small Computer System Interface)SCSI standards


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Drive Configuration Overview

The configuration of a hard drive usually includes setting jumpers on the drive, terminating properly, and performing a few software commands.

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PATA IDE Device Configuration

The steps for installing a PATA device: Do not remove the device from the anti-static bag until you are ready to

install. Follow proper anti-static procedure. Touch the device by the sides and

do not handle the electronics or connectors. Turn off the power and remove the power cord. Configure jumpers according to the number of devices to be attached to

the cable. Mount and secure the device. Attach the cables. Configure BIOS if needed. If the device is a hard drive prepare it as specified in the chapter.

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PATA IDE Device Configuration

PATA IDE Hard Drives are normally configured using jumpers.

– Single IDE setting is used when only one devices connects to the IDE cable.

– Master IDE setting is a jumper setting used to configure an IDE device and is the controlling device on the interface.

– Slave IDE setting is an IDE setting for the second device added to the IDE cable. The device should be a slower device than the master.

– Cable Select is a setting used on IDE devices when a special cable determines which device is the master and which one is the slave.

– DASP (Drive Active/Slave Present) is a signal in the ATA interface of the IDE connector that is used to indicate the presence of a slave IDE device.

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IDE Device ConfigurationIDE Motherboard Connectors


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IDE Device Configuration

Two PATA devices configured as cable select


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Serial ATA (SATA) Installation

Serial ATA drives are easy to install.– Serial ATA drives do not have any master/slave,

cable select, or termination settings.– Uses a small 7-pin connector that attaches between

the serial ATA controller and the serial ATA drive.

Installation instructions for serial ATA drives can be found on page 217.

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Serial ATA (SATA) InstallationInstalled SATA hard drive and adapter


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SCSI Configuration

A SCSI device is configured by:– Setting the proper SCSI ID– Terminating both ends of the SCSI chain– Connecting the proper cables

A SCSI ID is the priority number assigned to each device connected by a SCSI chain.

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SCSI ID Configuration

Standard SCSI devices recognize SCSI IDs 0 through 7.

Wide SCSI devices recognize SCSI IDs 0 through 15.

Power on all external SCSI devices before powering on the computer.

Each SCSI device must have a unique SCSI ID.– SCAM (SCSI Configured AutoMatically) allows

for automatic SCSI ID assignment.

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SCSI ID ConfigurationSCSI ID settings (most significant bit to the left)


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SCSI ID ConfigurationTwo Internal SCSI Devices – SCSI IDs


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SCSI ID ConfigurationTwo External SCSI Devices – SCSI IDs


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SCSI Termination

SCSI termination is performed in several different ways:

– By installing a SIPP

– By installing a jumper

– By setting a switch

– By installing a terminator plug

– By installing a pass-through terminator

– Through software

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SCSI Termination


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SCSI TerminationSCSI termination


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SCSI TerminationToday’s SCSI Terminators:

pass through terminator and 68-pin active terminator


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SCSI TerminationSCSI Symbols


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SCSI TerminationTwo internal SCSI devices - termination


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SCSI TerminationTwo external SCSI devices - termination


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SCSI TerminationInternal and external SCSI devices - termination


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SCSI Cables

SCSI cabling allows multiple devices to be connected to one SCSI host adapter and share the same SCSI bus.– Most internal SCSI-1 and SCSI-2 cables are 50-pin

ribbon cables. They are also known as an A cable.– Internal SCSI-3 cables are 68-pin ribbon cables.

When installing multiple SCSI devices, install one device at a time.

Always avoid using the cheaper, thinner SCSI cables. They are more susceptible to outside noise.

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SCSI Cables

Internal SCSI cables


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SCSI Cables

External SCSI cables


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SCSI CablesSCSI cables and connectors


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Laptop Storage Devices

• Laptops can use IDE or SCSI hard drives.

• Laptop IDE hard drives are installed using two methods:– Proprietary installation is installed in a location that

cannot be changed, configured, or moved very easily.

– Removable IDE hard drives with a laptop are installed or removed through a 44-pin connector.

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System BIOS Configuration for Hard Drives

Hard drives are configured through the Setup program with a drive type number.– IDE hard drives are normally configured using the

Auto-Detect feature included with BIOS. This feature automatically determines the drive type for the system.

– For SCSI hard drive installation the most common CMOS setting for the hard drive type is none or type 0.

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Hard Drive Preparation Overview

Two steps to hard drive preparation:– Partition– High-Level Format

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Partitioning

Partitioning divides a hard drive so that the computer system sees more than one drive.

– FDISK is a command used in DOS and Windows 9x to partition a hard drive.

– Disk Administrator – Windows NT/2000/XP also allow partitions to be set up using the Disk Administrator program.

A File System defines how data is stored on a drive.

– FAT (File Allocation Table) is a method of organizing a computer’s file system.

– FAT16 file system is supported by DOS, Windows 9x, NT, 2000, and XP.

– FAT32 file system used by Windows 95 Service Release 2, Windows 98, Windows 2000, and XP that supports hard drives up to 2TB in size.

– NTFS (NT File System) file system used with Windows NT, 2000, and XP.

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Partitioning

Types of Partitions:

– The Primary Partition is the first detected drive on the hard drive.

– The Extended Partition is a hard drive division

– Logical Drives divides the extended partition into separate units which appear as separate drive letters.

– System Partition is a type of active hard drive partition found in Windows NT and 2000 that contains the hardware-specific files needed to load the operating system.

– Boot Partition – A type of partition found in Windows NT and 2000 that contains the operating system.

The Partition Table holds the information about the types and locations of partitions created. It is part of the master boot record.

MBR (Master Boot Record) is a program that reads the partition table to find the primary partitions used to boot the system.

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PartitioningClusters


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Partitioning

FAT16 partitions and cluster size


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Partitioning

FAT32 partitions and cluster size


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PartitioningNTFS partitions and cluster size


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PartitioningWindows XP’s Disk Administrator


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PartitioningHard drive partitioning


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PartitioningTwo logical drives


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How Drive Letters Are Assigned

The order in which the partitions are assigned drive letters depends on three factors:– The number of hard drives.– The type of partitions on the hard drives.– The operating system.

The first floppy drive detected is assigned drive letter A:. The second floppy drive detected is assigned drive letter B:. If a second floppy

drive is not found a logical drive B: is created an assigned to the first floppy drive.

The first primary partition marked active receives drive letter C:. Logical drives on hard drives and removable devices are assigned letters. Remaining primary partitions are assigned letters. CD and DVD drives are assigned letters.

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Windows 2000/XP Logical Disk Management Dynamic disks can have different types of volumes:

– Simple Volume is disk space allocated from one hard drive.

– Spanned Volume is disk space created from multiple hard drives.

– Striped Volume is when data is written across two to thirty-two hard drives.

– Raid 5 Volume puts data on three or more hard drives and one of the hard drive spaces is used for parity.

– System Volume holds the files needed to boot the operating system.

– Boot Volume holds the remaining operating system files. The system volume and the boot volume can be one and the same.

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Fault Tolerance

RAID (Redundant Array of Independent (formerly Inexpensive) Disks allows writing

to multiple hard drives for larger storage areas, fault tolerance, and better performance.

Fault Tolerance is the ability to continue functioning after a hardware or software

failure.

Different RAID levels

– RAID Level 0 is also called disk striping without parity. It does not protect data

when a hard drive fails.

– RAID Level 1 is called disk mirroring or disk duplexing.

Disk mirroring uses two or more hard drives and one disk controller.

Disk duplexing uses two or more hard drives and two disk controllers.

– RAID Level 5 is also called disk striping with parity. It writes data to three or

more hard drives and includes parity information with the data.

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Bootable Disks

A bootable CD or disk is at times the only way to get the repair process started when a hard drive has trouble booting. – ERD (Emergency Repair Disk) is a copy of the

REPAIR folder created when backing up the registry in Windows 2000 Professional and NT Workstation. This can help when the operating system has problems booting.

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Troubleshooting Drives

Problems with new drive installations:– Improper jumper configuration– SCSI ID settings– Termination– Problems with cabling– Drive type configuration

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Troubleshooting Drives

Problems with hard drives that worked previously:– Check for viruses.– Check for resource conflicts from any new

hardware or software that was installed.– Check for loose cables.– Verify bootable system files.– Verify that the hard drive is still operational.

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SCSI Specific Errors

Problems with SCSI hard drives:– Check for incorrect termination.– Check the SCSI ID for the drives.– Check the SCSI adapter’s resources assigned.

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Preventive Maintenance for Hard Drives

Preventive Maintenance will prolong the life of the computer.

– CHKDSK is a program that locates clusters disassociated from data files.Lost Clusters are sectors on a disk that the file allocation

table cannot associate with any file or directory.

– SCANDISK is a software program used to detect and repair lost clusters.

– Disk Cleanup is a Windows 2000 and XP utility that helps free up hard drive space by emptying the Recycle Bin, removing temporary files, etc.

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Data Security

• As preventative maintenance perform a backup of data and the operating system.

• The most important part of a computer is the data within it.

• Backups can be completed on magnetic tape and/or CD/DVDs.

• Thin-client environment – systems in which no hard drive is included and data is stored on the network. This is a new, popular option with many companies.

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Removable Drive Storage

• IDE and SCSI are also used for internal and external storage devices such as CD/DVD drives and tape drives.

• A popular option is to attach these devices through a USB port.

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Hard Drive Fragmentation

• Over time files will become fragmented on a hard drive and slow down access time.– Defragmentation – the process of placing files in

contiguous sectors. Defragmentation allows for faster hard disk access of files.

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Hard Drive FragmentationFragmented hard drive


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Disk Caching/Virtual Memory

Ways to speed up the hard drive:

– Disk Cache or Data Buffer is a portion of RAM set aside for hard drive data that speeds up hard drive operations.

– VMM (Virtual Memory Manager) is a Windows component that uses hard disk space as if it were RAM.

It is best to put the swap file on a the fastest hard drive that doesn’t contain the operating system.

Virtual memory swap file size can be adjusted.

7-1 Hard Drive. 7-2 Section Objectives After completing this section you will be able to: Install or replace a floppy drive Define and explain fundamental.

Documents

floppy drive heads

floppy drive overview

floppy drive subsystem

floppy drive instructions

floppy cable slide

floppy media disk

floppy drive installation

floppy disk geometry