A+ Guide to Managing and Maintaining your PC, 6e · A+ Guide to Managing and Maintaining your PC, 6e 4 How Floppy Drives Work •Main memory is organized logically and physically

A+ Guide to Managing and

Maintaining your PC, 6e

Chapter 8

Hard Drives

A+ Guide to Managing and Maintaining your PC, 6e 2

Introduction

• Hard drive: most important secondary storage device

• Hard drive technologies have evolved rapidly

– Hard drive capacities and speeds have increased

– Interfaces with the computer have also changed

• Floppy disk will be presented before hard drives

– Floppy disk is logically organized like a hard drive

• Practical applications:

– Managing problems occurring during drive installation

– Troubleshooting hard drives after installation


Learning from Floppy Drives

• Floppy drives are an obsolescent technology

– Replacements: CD drives and USB flash memory

• Good reasons for studying floppy drive technology

– Developing support skills for legacy applications

– Building a foundation for hard drive support skill set


How Floppy Drives Work

• Main memory is organized logically and physically

• Secondary storage devices are similarly organized

– Physical storage: how data is written to media

– Logical storage: how OS and BIOS view stored data

• How data is physically stored on a floppy disk

– Two types of floppy disk: 5 ¼ inch or 3 ½ inch

– Subsystem: drive, 34-pin cable, connector, power cord

– Formatting: marking tracks and sectors on a disk

– Magnetic read/write heads read/write binary 1s and 0s

– Heads attach to actuator arm that moves over surface


Figure 8-4 3 1 -inch, high-density floppy disk showing tracks and sectors


Figure 8-5 Inside a floppy disk drive


How Floppy Drives Work (continued)

• How data is logically stored on a floppy disk

– Floppy drives are always formatted using FAT12

– Cluster (file allocation unit): smallest grouping of sectors

– The BIOS manages the disk as a set of physical sectors

– OS treats the disk as list of clusters (file allocation table)

– A 3 ½ inch high density floppy disk has 2880 clusters

• A cluster contains one sector, which contains 512 bytes

• Format floppy disk using Format or Windows Explorer

– Structures and features added to the disk

• Tracks, sectors, boot record, two FATs, root directory


Figure 8-6 Clusters, or file allocation units, are managed

by the OS in the file allocation table, but BIOS manages

these clusters as one or two physical sectors on the disk


How to Install a Floppy Drive

• It is more cost-effective to replace than repair a drive

• A simple seven-step installation procedure:

– 1. Turn off computer, unplug power cord, remove cover

– 2. Unplug the power cable to the old floppy drive

– 3. Unscrew and dismount the drive

– 4. Slide the new drive into the bay

– 5. If drive is new, connect data cable to motherboard

– 6. Connect data cable and power cord to drive

– 7. Replace the cover, turn on computer, verify status


Figure 8-8 Connect colored edge of cable to pin 1


How Hard Drives Work

• Components of a hard drive:

– One, two, or more platters (disks)

– Spindle to rotate all disks

– Magnetic coating on disk to store bits of data

– Read/write head at the top and bottom of each disk

– Actuator to move read/write head over disk surface

– Hard drive controller: chip directing read/write head

• Head (surface) of platter is not the read/write head

• Physical organization includes a cylinder

– All tracks that are the same distance from disk center


Figure 8-10 Inside a hard drive case


Figure 8-11 A hard drive with two platters


Tracks and Sectors on the Drive

• Tracks on older drives held the same amount of data

• Newer drives use zone bit recording

– Tracks near center have smallest number sectors/track

– Number of sectors increase as tracks grow larger

– Every sector still has 512 bytes

– Sectors identified with logical block addressing (LBA)


Figure 8-13 Floppy drives and older hard drives use a

constant number of sectors per track


Figure 8-14 Zone bit recording can have more sectors

per track as the tracks get larger


Low-Level Formatting

• Two formatting levels:

– Low-level: mark tracks and sectors

– High-level: create boot sector, file system, root directory

• Manufacturer currently perform most low-level formats

– Using the wrong format program could destroy drive

– If necessary, contact manufacturer for format program

• Problem: track and sector markings fade

– Solution for older drives: perform low-level format

– Solution for new drive: backup data and replace drive

• Note: zero-fill utilities do not do low-level formats


Calculating Drive Capacity on Older

Drives

• Constant number of sectors per track

• The formula was straightforward:

– Cylinders x heads x sectors/track x 512 bytes/sector

• Example: 855 cylinders, 7 heads, 17 sectors/track

– 855 x 7 x 17 x 512 bytes/sector = 52,093,440 bytes

– Divide by 1024 twice to convert to 49.68 MB capacity


Drive Capacity for Today’s Drives

• The OS reports the capacity of hard drives

• Accessing capacity data using Windows Explorer

– Right-click the drive letter

– Select Properties on the shortcut menu

• Calculating total capacity if drive is fully formatted

– Record capacity of each logical drive on hard drive

– Add individual capacities to calculate total capacity

• Reporting total capacity (regardless of formatting)

– Windows 2000/XP: use Disk Management

– Windows 9x: use Fdisk


Hard Drive Interface Standards

• Facilitate communication with the computer system

• Several standards exist:

– Several ATA standards

– SCSI

– USB

– FireWire (also called 1394)

– Fibre Channel

• The various standards will be covered


The ATA Interface Standards

• Specify how drives communicate with PC system

– Drive controller interaction with BIOS, chipset, OS

– Type of connectors used by the drive

– The motherboard or expansion cards

• Developed by Technical Committee T13

• Published by ANSI

• Selection criteria:

– Fastest standard that the motherboard supports

– OS, BIOS, and drive firmware must support standard


Table 8-1 Summary of ATA interface standards for storage devices



(continued)

• Parallel ATA

– Allows two connectors for two 40-pin data cables

– Ribbon cables can accommodate one or two drives

• EIDE (Enhanced Integrated Device Electronics)

– Pertains to how secondary storage device works

– Drive follows AT Attachment Packet Interface (ATAPI)

– Four parallel ATA devices can attach with two cables

• Serial ATA (SATA) cabling

– Use a serial data path rather than a parallel data path

– Types of SATA cabling: internal and external


Figure 8-16 A PC’s hard drive subsystem using parallel ATA


Figure 8-18 A hard drive subsystem using the new serial ATA data cable



(continued)

• DMA (direct memory access) transfer mode

– 7 modes (0 - 6) bypassing CPU in transfer of data

• PIO (Programmed Input/Output) transfer mode

– 5 modes (0 - 4) involving CPU in data transfer

• Independent device timing

– Enables two drives to run at different speed

• ATA/ATAPI-6 (ATA/100) breaks the 137 GB barrier

– Addressable space is 144 petabytes (1.44 x 1017 PB)

– Must have support of board, BIOS, OS, IDE controller


Figure 8-21 The 137-GB barrier existed because of the size of

the numbers used to address a sector



(continued)

• Configuring parallel ATA drives

– Each of two IDE connectors supports an IDE channel

– Primary/secondary channels each support two devices

– EIDE devices: hard drive, DVD, CD and Zip drives

– Devices in each channel configured as master/slave

– Designate master/slave: jumpers, DIP switches, cable

• Configuring serial ATA drives

– One ATA cable supports one drive (no master/slave)

• Use an ATA controller card in two circumstances:

– IDE connector not functioning or standard not supported


Figure 8-22 A motherboard has two IDE

channels; each can support a master and

slave drive using a single EIDE cable


Figure 8-25 Rear of a serial ATA drive and a parallel ATA drive


SCSI Technology

• Small Computer System Interface standards

– For system bus to peripheral device communication

– Support either 7 or 15 devices (depends on standard)

– Provide for better performance than ATA standards

• The SCSI subsystem

– SCSI controller types: embedded or host adapter

– Host adapter supports internal and external devices

– Daisy chain: combination of host adapter and devices

– Each device on bus assigned SCSI ID (0 - 15)

– A physical device can embed multiple logical devices


Figure 8-28 Using a SCSI bus, a SCSI host adapter can

support internal and external SCSI devices


SCSI Technology (continued)

• Terminating resistor

– Plugged into last device at the end of the chain

– Reduces electrical noise or interference on the cable

• Various SCSI standards

– SCSI are SCSI-1, SCSI-2, and SCSI-3

• Also known as regular SCSI, Fast SCSI, Ultra SCSI

– Serial attached SCSI (SAS): compatible with serial ATA

– Ensure all components of subsystem use one standard


Other Interface Standards

• USB (Universal Serial Bus)

– USB 1.1 and USB 2.0 accommodate hard drives

– A USB device connects to a PC via a USB port

• IEEE 1394 (FireWire)

– Uses serial transmission of data

– Device can connect to PC via FireWire external port

– Device also attaches to an internal connector

• Fibre Channel

– Rival to SCSI

– Allows up to 126 devices on a single bus


Figure 8-31 This CrossFire hard drive holds 160GB

and uses a 1394a or USB 2.0 connection


How to Select a Hard Drive

• Hard drive must match OS and motherboard

• BIOS uses autodetection to prepare the device

– Drive capacity and configuration are selected

– Best possible ATA standard is part of configuration

• Selected device may not supported by BIOS

• Troubleshooting tasks (if device is not recognized)

– Flash the BIOS

– Replace the controller card

– Replace the motherboard


Installations Using Legacy BIOS

• Older hard drive standards that may be encountered

– CHS (cylinder, head, track) mode for drives < 528 MB

– Large (ECHS) mode for drives from 504 MB - 8.4 GB

– The 33.8 GB limitation or the 137 GB limitation

• How to install a drive not supported by BIOS

– Let the BIOS see the drive as a smaller drive

– Upgrade the BIOS

– Replace the motherboard

– Use a software interface between BIOS and drive

– Substitute BIOS with ATA connector and firmware


Steps to Install a Parallel ATA Drive

• Components needed:

– The drive itself

– 80-conductor or 40-conductor data cable

– Kit to make drive fit into much larger bay (optional)

– Adapter card (if board does not have IDE connection)

• Steps for installing parallel ATA drive:

– Step 1: Prepare for the installation

• Know your starting point

• Read the documentation

• Plan the drive configuration

• Prepare your work area and take precautions


Figure 8-32 Plan for the location of drives within bays



(continued)

• Steps for installing parallel ATA drive (continued):

– Step 2: Set the jumpers or DIP switches

– Step 3: Mount the drive in the drive bay

• Remove the bay for the hard drive

• Securely mount the drive in the bay

• Connect the data cables to the drives (can be done later)

• Re-insert (and secure) the bay in the case

• Install a power connection to each drive

• Connect the data cable to the IDE connector on board

• Attach bay cover and other connections (if needed)

• Verify BIOS recognizes device before adding cover


Figure 8-33 A parallel ATA drive most likely will have

diagrams of jumper settings for master and slave

options printed on the drive housing


Figure 8-41 Connect a power cord to each drive



(continued)

• Steps for installing parallel ATA drive (continued):

– Step 4: Use CMOS setup to verify hard drive settings

– Step 5: Partition and format the drive

• If installing an OS, boot from Windows setup CD

• If not, use Disk Management utility or Fdisk and Format


Figure 8-45 Standard CMOS setup


Serial ATA Hard Drive Installations

• No jumpers to set on the drive

• Each serial ATA connector is dedicated to 1 drive

• A simpler installation process:

– Install the drive in the bay (like parallel ATA drive)

– Connect a power cord to the drive

• Documentation identifies which connector to use

– Example: use red connectors (SATA1, SATA2) first

• After checking connections, verify drive is recognized


Figure 8-48 This motherboard has four serial ATA connectors


Figure 8-49 American Megatrends, Inc. CMOS setup

screen shows installed drives


Installing a Hard Drive in a Wide Bay

• Universal bay kit: adapts a drive to a wide bay

• Adapter spans distance between drive and bay


Figure 8-52 Hard drive installed in a wide bay using a

universal bay kit adapter


Troubleshooting Hard Drives

• Problems occur before and after installation

• Problems may be hardware or software related

• Hardware-related problems will be addressed


Problems with Hard Drive Installations

• CMOS setup does not reflect new hard drive

– Solution: Enable autodetection and reboot system

• Error message: “ Hard drive not found.”

– Reseat the data cable and reboot the PC

• Error message: “No boot device available.”

– Insert bootable disk and restart the machine

• Error message 601 appears on the screen

– Connect the power cord to the floppy disk drive

• Error message: “Hard drive not present”

– Restore jumpers to their original state


Problems with Hard Drive Installations

(continued)

• Things to check if CMOS setup does not show drive

– Does your system BIOS recognize large drives?

– Is autodetection correctly configured in CMOS setup?

– Are the jumpers on the drive set correctly?

– Are the power cord and data cable connected?


How to Approach a Hard Drive

Problem After the Installation

• Some post-installation problems

– Corrupted data files

– A corrupted Windows installation

– A hardware issue preventing system from booting

• Preparation steps

– Start with the end user: conduct an interview

– Prioritize what you have learned

• Example: make data backup your first priority

– Be aware of available resources

• Examples: documentation, Internet, Technical Support


Hard Drive Hardware Problems

• Causes of problems present during boot:

– Hard drive subsystem

– Partition table

– File system on the drive

– Files required for the OS to boot

• Some things to do if POST reveals problem

– Check the jumper settings on the drive

– Check the cable for frayed edges or other damage

– Try booting from another media; e.g. setup CD

– Check manufacturer Web site for diagnostic software


Hard Drive Hardware Problems

(continued)

• Bumps are bad

– A scratched surface may cause a hard drive crash

– Data may be recovered, even if drive is inaccessible

• Invalid drive or drive specification

– System BIOS cannot read partition table information

– Boot from recovery CD and check partition table

– To be covered in later chapters

• Bad sector errors

– Problem due to fading tracks and sectors

– Solution: replace the drive


Troubleshooting Floppy Drives and

Disks

• Table 8-4 has two columns

– One identifies errors occurring before and after boot

– Another displays troubleshooting tasks


Table 8-4 Floppy drive and floppy disk errors that can occur during

and after the boot


Table 8-4 Floppy drive and floppy disk errors that can occur during

and after the boot (continued)

A+ Guide to Managing and Maintaining your PC, 6e · A+ Guide to Managing and Maintaining your PC, 6e 4 How Floppy Drives Work •Main memory is organized logically and physically

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