A+ Guide to Managing and
Maintaining your PC, 6e
Chapter 8
Hard Drives (v0.9)
Learning from Floppy Drives
• Floppy drives are an obsolescent
technology
– Replacements: CD drives and USB flash
memory
• Good reasons for studying floppy drive
technology
– Very similar technology with hard disk drives
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How Floppy Disks 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
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How Data is Stored
• 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
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Figure 8-4 3 1 -inch, high-density floppy disk showing tracks and sectors
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Figure 8-5 Inside a floppy disk drive
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How Floppy Drives Work (continued)
• How data is logically stored on a floppy disk
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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
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Floppy Disk Formatting
• Use command prompt FORMAT
command
• Use Windows Explorer
• Structures and features added to the
disk
– Tracks, sectors, boot record, two FATs,
root directory
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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
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Figure 8-8 Connect colored edge of cable to pin 1
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Hard Drives
• Larger storage capacity
• General construction
– Rigid platters
– Spindle speeds 5600 to 15,000 rpm
– Sealed environment
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How Hard Drives Work
• Components of a hard drive:
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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
• Physical organization includes a cylinder
– All tracks that are the same distance from disk center
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Figure 8-10 Inside a hard drive case
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Figure 8-11 A hard drive with two platters
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Tracks and Sectors on the Drive
• Tracks on older drives held the same amount of data
• Newer drives use zone bit recording
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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)
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Figure 8-13 Floppy drives and older hard drives use a
constant number of sectors per track
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Figure 8-14 Zone bit recording can have more sectors
per track as the tracks get larger
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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
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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
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Hard Drive Interface Standards
• Facilitate communication with the computer
system
• Several standards exist:
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Several ATA standards
SCSI
USB
FireWire (also called 1394)
Fibre Channel
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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
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Table 8-1 Summary of ATA interface standards for storage devices
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The ATA Interface Standards
(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
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SATA
• Use a serial data path rather than a
parallel data path
• Types of SATA cabling: internal and
external
• SATA 150 and SATA 300
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Figure 8-16 A PC’s hard drive subsystem using parallel ATA
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Figure 8-18 A hard drive subsystem using the new serial ATA data cable
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The ATA Interface Standards
(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
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Figure 8-21 The 137-GB barrier existed because of the size of
the numbers used to address a sector
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The ATA Interface Standards
(continued)
• Configuring parallel ATA drives
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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
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Figure 8-22 A motherboard has two IDE
channels; each can support a master and
slave drive using a single EIDE cable
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Figure 8-25 Rear of a serial ATA drive and a parallel ATA drive
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SCSI Technology
• Small Computer System Interface
standards
– For system bus to peripheral device
communication
– Support either 7 or 15 devices (depends on
standard)
– Can have better performance than ATA
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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
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Figure 8-28 Using a SCSI bus, a SCSI host adapter can
support internal and external SCSI devices
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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
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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
– Allows up to 126 devices on a single bus
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Figure 8-31 This CrossFire hard drive holds 160GB
and uses a 1394a or USB 2.0 connection
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How to Select a Hard Drive
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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
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Selected device may not supported by BIOS
Troubleshooting tasks (if device is not recognized)
– Flash the BIOS
– Replace the controller card
– Replace the motherboard
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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
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Drive Installation 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 adapter/firmware
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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)
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Steps to Install a Parallel ATA Drive
• Step 1: Prepare for the installation
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Know your starting point
Read the documentation
Plan the drive configuration
Prepare your work area and take
precautions
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Figure 8-32 Plan for the location of drives within bays
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Steps to Install a Parallel ATA Drive
(continued)
• Steps for installing parallel ATA drive
(continued):
– Step 2: Set the jumpers or DIP switches
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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
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Steps to Install a Parallel ATA Drive
(continued)
• 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
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Figure 8-41 Connect a power cord to each drive
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Steps to Install a Parallel ATA 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
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Figure 8-45 Standard CMOS setup
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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
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Figure 8-48 This motherboard has four serial ATA connectors
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Figure 8-49 American Megatrends, Inc. CMOS setup
screen shows installed drives
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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
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Figure 8-52 Hard drive installed in a wide bay using a
universal bay kit adapter
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Troubleshooting Hard Drives
• Problems occur before and after installation
• Problems may be hardware or software
related
• Hardware-related problems will be
addressed
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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
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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?
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Hard Drive Hardware Problems
• Causes of problems present during boot:
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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
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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
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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
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