imd 203 - ch08

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

Chapter 8Hard Drives

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


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


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


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



• 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



• 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


Steps to Install a Parallel ATA Drive (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


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


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)


Summary

• Current floppy disks are 3 ½ inch, high-density disks

• Floppy disk format: 80 tracks, each with 8 sectors

• Hard drive physical organization: cylinders, tracks, sectors

• Hard drive logical organization: boot record, file allocation tables, and root directory

• Secondary storage device communicates with system using a standard, such as ATA or SCSI


Summary (continued)

• Parallel ATA (or EIDE): allows connection of up to 4 devices

• Serial ATA (SATA): specifies one cable per device

• SCSI group: allow up to 7 or 15 physical devices and multiple logical devices per physical device

• Other drive interface standards: USB, FireWire, Fibre Channel

• Newly installed hard drives are usually automatically detected by BIOS

imd 203 - ch08

Education

floppy disk drive

drive tracks

drive capacity

floppy drives floppy

hard drives floppy disk

floppy disk floppy drives

hard drive problems

hard drive capacities