A Guide to Hardware, 4e

1
A Guide to Hardware, 4e

• Chapter 7
• Hard Drives

2
Objectives

• Learn how the organization of data on floppy
  drives and hard drives is similar
• Learn about hard drive technologies
• Learn how a computer communicates with a hard
  drive
• Learn how to install a hard drive
• Learn how to solve hard drive problems

3
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

4
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

5
Figure 7-4 3 1 -inch, high-density floppy disk
showing tracks and sectors
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Figure 7-5 Inside a floppy disk drive
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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

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Figure 7-8 Connect colored edge of cable to pin 1
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Figure 7-10 Inside a hard drive case
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Figure 7-13 Floppy drives and older hard drives
use a constant number of sectors per track
Figure 7-14 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
• Note zero-fill utilities do not do low-level
  formats

12
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

13
Drive Capacity for Todays 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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Table 7-1 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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Figure 7-16 A PCs hard drive subsystem using
parallel ATA
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Figure 7-18 A hard drive subsystem using the new
serial ATA data cable
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Figure 7-25 Rear of a serial ATA drive and a
parallel ATA drive
19
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

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Figure 7-28 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
• Rival to SCSI
• Allows up to 126 devices on a single bus

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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

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Installations Using Legacy BIOS

• Older hard drive standards that may be
  encountered
• CHS (cylinder, head, track) mode for drives lt 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

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Figure 7-33 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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Figure 7-45 Standard CMOS setup
27
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

28
Troubleshooting Hard Drives

• Problems occur before and after installation
• Problems may be hardware or software related
• Hardware-related problems will be addressed

29
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?

31
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

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Troubleshooting Floppy Drives and Disks

• Table 7-4 has two columns
• One identifies errors occurring before and after
  boot
• Another displays troubleshooting tasks