hard drive. drive capacity measurementcontainsusually used for measuring size of kb (kilobytes 1,024...
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Hard Drive
Drive Capacity
Measurement Contains Usually Used for Measuring Size Of
KB (kilobytes 1,024 bytes Floppy drives
MB (megabytes)
1,024 KB DCs, small hard drives, cartridge drives, small tape drives
GB (gigabytes 1,024 MBHard drives, large capacity cartridge drives, some tape drives, and DVDs
TB (terabytes) 1,024 GB Very large hard drives and some tape drives
Hard Drive ArchitectureVoice coil actuatorVoice coil actuator Read/write headsRead/write heads SpindleSpindle PlattersPlatters
Side 0Side 0
Side 1 (underside)
Side 1 (underside)
Side 2Side 2
Side 3(underside)
Side 3(underside)
Actuator armsActuator arms
Disk Drive Geometry
TrackTrack
SectorSector
CylinderCylinder
Traditional Sectors
Zoned-Bit Recording Sectors
Sector Interleave
How Hard Drives Work
7200 RPM
HeadHead
Form Factor
3.5-inch drive3.5-inch drive
5.25-inch drive5.25-inch drive
IDE Hard Drive
IDE data cableIDE data cable Red stripe indicates Pin 1
Red stripe indicates Pin 1
Jumpers to specify master, slave, or cable select
Jumpers to specify master, slave, or cable select
Power cablePower cable
Primary and Secondary IDE Drives
Motherboard
Set as slave
DVD driveDVD drive
CD-RW driveCD-RW drive
Set as master
Set as master
HD0 boot driveHD0 boot drive
Set as a slave
HD1 second hard driveHD1 second hard drive
Secondary IDESecondary IDE
Primary IDEPrimary IDE
Connect IDE Drives to the Cable
Connect to masterConnect to master
Connect to slave or singleConnect to slave or single
Ultra DMA DrivesAn extension of the ATA disk interfaceTransfer rates of 33, 66, or 100 MBpsBackward compatible with EIDE system
boards and controllers (but speed limited to 16.6 MBps)
Partitioning
A partition is an isolated section of a disk that functions like a separate physical drive. Partitions enable you to create a logical disk structure to organize hard drives.
Formatting
Formatting is a system function that prepares a mass storage medium to hold data. Each partition on a drive is formatted separately.
SCSI Chain
HBAHBAInternal driveInternal drive
Externaltape driveExternal
tape drive
External CD-ROM drive
External CD-ROM drive
SCSI Device IDsBy switchBy switch
By jumperBy jumper
SCSI Binary Jumper Settings
Technique Description
Single-Ended (SE)Uses a single wire for each bit of data. Cable length is limited to 6 meters due to noise.
High Voltage Differential (HVD) Signaling
Also known as differential signaling. Uses two wires for each data bit—one for the actual data and one for the inverse of the data. By comparing the data and its inverse, noise can be identified and rejected. Cable length can be up to 25 meters. Connecting an HVD device in an SE chain damages SE devices and sometimes also the HVD devices.
Low Voltage Differential (LVD) Signaling
Uses less power than HVD devices and can be chained with SE devices without damaging any devices. An LVD device on an SE chain will function like an SE device, so you lose the advantages of differential signaling. LVD cabling is limited to 12 meters.
SCSI Signaling Techniques
SCSI Termination SCSI chain termination
By terminating resistorBy terminating resistor
By switchBy switch
By jumperBy jumper
SCSI Type Description
SCSI-1 (narrow SCSI or regular SCSI)
8 bits wide. Supports up to 8 devices (7 plus the HBA). Uses a 50-pin connector; transfers data at up to 5 MB per second.
Wide SCSI 16 bits wide. Supports up to 16 devices (15 plus the HBA). Transfers data at up to 20 MB per second.
Ultra Wide SCSI 16 bits wide. The 50-pin (or lower) connections carry one byte at a time. Ultra Wide connections carry two bytes at a time. Transfers data at up to 40 MB per second.
Fast SCSI 8 bits wide. Transfers data at up to 10 MB per second.
Fast Wide SCSI 16 bits wide. Transfers data at up to 20 MB per second.
Ultra SCSI 16 bits wide. Transfers data at up to 40 MB per second. If implemented on an 8-bit bus, data is transferred at up to 20 MB per second.
Ultra2 SCSI 16 bits wide. Transfers data at up to 80 MB per second. If implemented on an 8-bit bus, data is transferred at up to 40 MB per second.
Ultra3 SCSI 16 bits wide. Transfers data at up to 160 MB per second. If implemented on an 8-bit bus, data is transferred at up to 80 MB per second.
Ultra 320 SCSI 16 bits wide. Transfers data at up to 320 MB per second. If implemented on an 8-bit bus, data is transferred at up to 160 MB per second.
SCSI Types
External SCSI Connectors
SCSI 1 External ASCSI 1 External A
SCSI DB 25SCSI DB 25
SCSI 2 External ASCSI 2 External A
Internal SCSI Connectors
HBA is installed in the computer
Connector on HBA to internal SCSI flat cable
Connector from SCSI flat cable to SCSI drive
Symptom Possible Problem Solution
Error message at boot Drive Not Ready-System Halted
Drive is damaged.Drive is not configured for Master or Cable Select as appropriate to the system.Data cable is not connected or incorrectly connected to the drive.
Visually inspect the drive and its connections; correct as needed.
POST error codes in the 17xx range
1701: Drive not found.1702: Hard drive adapter not found.1703: Hard drive failure.1704: Hard drive or adapter failure.1780, 1790: Hard drive 0 failed.1781, 1791: Hard drive 1 failed.1782: Hard drive controller failed.
Visually inspect connections and reconnect drive. Replace failed component.
Common Problems with Hard Drives
Symptom Possible Problem Solution
Can’t read from or write to the drive
Bad sectors on the drive.IRQ conflicts.Drive failure.Virus attack.
Run Scandisk to try to recover information from bad sectors and to mark those sectors as unusable.Check Device Manager for hardware resource conflicts and for indications of drive failure.Run virus check software and remove any viruses found.
System will not bootDrive disconnected, damaged, or not recognized by the BIOS.
Visually inspect and reconnect drive. Enable drive in CMOS setup utility.
Drive is making grinding noises that keep repeating in a regular pattern
Physically damaged drive, most likely due to a head crash.
Replace the hard drive. Remind users and technicians not to move a machine while it is in use since that is the most common cause of head crashes.
Data is frequently being corrupted or utilities are not running properly
System not being shut down properly; drive is in the process of failing; virus.
Educate users on how to properly shut down the system. Run virus protection software. Back up the data. Replace failed or failing drive.
Common Problems with Hard Drives (Cont.)
IDE Drive Troubleshooting If you have one drive on a channel, it must
be configured as single—not master or slave. With two drives on a channel, set both to
cable select or configure them both manually, setting one to master and the other to slave.
If you remove the second IDE hard disk from a computer with two IDE drives installed, verify that the disk that remains in the computer is set as single.
If you need to move an IDE drive from one computer to another, you likely won't run into problems.
SCSI Drive Troubleshooting Most problems with SCSI disks are due to incorrect ID
settings and improper termination. When a SCSI system is booted or reset, SCSI controllers
generally need to renew all SCSI device connections before activating the devices, causing a delay during POST.
SCSI cables should be handled carefully to minimize problems.
If you intend for a SCSI disk to be bootable after you install it, you must enable the SCSI BIOS.
Verify that all SCSI devices have unique SCSI ID numbers. When installing an additional SCSI hard drive into a
computer where only one connector is available on the SCSI cable and the cable itself is terminated, remove and replace the cable with one that has multiple connectors.
Slow Drives Drive is too full—Windows needs free
drive space to write temporary and swap files.
Fragmentation—Run a disk defragmenter program monthly to clean up defragmentation and put files in contiguous blocks.
Controller too slow—If you have a fast drive connected to a slower controller, the drive will transfer data at the slower rate.
The wrong cable is used—If you use a cable for a slower drive, it can result in decreased performance.
Utility Description Syntax
chkdsk
Enables you to check the hard disk for errors. If any errors are reported, you can then use other tools such as ScanDisk to repair those errors.
At a command prompt, enter chkdsk drive letter. For example, to check the C drive, enter chkdsk C:.
Disk Defragmenter (Defrag.exe)
Rearranges the files on your computer's hard disk to make them contiguous. Use Disk Defragmenter when a hard disk's performance has slowed down.
Choose Start→All Programs→Accessories→System Tools→Disk Defragmenter, or choose Start→Run and enter defrag in the Open text box.
Disk Management
Windows XP's graphical tool for managing drives and partitions.
From the Start menu, right-click My Computer and choose Manage. Select Disk Management in the Computer Management window.
Fdisk.exe and Format.exe
DOS-based disk and file-management tools; Fdisk is for disk partitioning and Format is for formatting.
Boot with a bootable DOS floppy disk containing the utilities and run them at the command prompt.
Scandisk (Scandisk.exe)
Scans and repairs problems with your computer's hard disk.
Choose Start→All Programs→Accessories→System Tools→ScanDisk, or choose Start→Run and enter scandisk in the Open text box.
Hard Drive Maintenance Tools
Striping with RAID Level 0
Data is divided across all drives.
DD AA TT AA
DATA
RAID Level 1Mirroring
Drive 0 Drive 1
Duplexing
Drive 0 Drive 1
DATADATA
DATA DATA
DATADATA DATADATA DATADATA
RAID Level 5
DD
DD
DDDD
ParityParity
ParityParity
AA
DD
AA
AA
ParityParity
TT
AA
AATT ParityParity
AA
TT
TT
TT
ParityParity
AA
AA
AAAA
DATA