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Hardware Emergency Room:   Hard Disk
 
Contents: Storage Media - Hard Drives
EIDE
SCSI
Hard Disk Upgrades
Hard Drive Problems
Data Recovery Solutions

Storage Media - Hard Drives
There are numerous types of drives used for storing computer data; these include floppy drives, hard drives, CD-ROM drives and so on.  These drives use differing types of technologies to store information, including magnetic and optical storage.  Modern hard disks consist of one or more magnetic disks contained in a box that is typically 3.5 inches in diameter.  Size and speed of the hard drive are decisive factors in a computer's performance.

A disk drive is made up of a disk that stores information, a motor that rotates the disk, a magnet, and an actuator with read/write heads attached to suspension arms that magnetically and electronically read and write information on the disk surface.

When the motor is powered up the disk rotates and causes the read/write heads to fly above the disk surface on a cushion of air.  They are two or three microns above the surface, and the disk can rotate up to 7200 RPM or more, which means that the heads can be traveling at speeds in excess of 64 miles per hour.  Under normal operation there is never any head to disk contact.

Hard Disk
disk
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Magnetic Disk
diskinside
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EIDE

Hard drives can be distinguished by their interface types.  Today's systems generally have either EIDE controllers or SCSI controllers.  EIDE (Enhanced Integrated Device Electronics) is the current standard for inexpensive, high performance hard disks.  EIDE controllers are integrated onto motherboards.  Most modern BIOS software can auto detect an EIDE disk, allowing it to work immediately once it is installed.  The hard disk is connected to the motherboard by means of an EIDE signal cable.  Each motherboard has sockets for two EIDE cables (a primary channel and a secondary channel), and has connectors for two units (a master and a slave) on each channel.  

EIDE Cable
eide
(Click to Enlarge)

IDE Sockets
ideslots
(Click to Enlarge)

A new PC will usually have two EIDE units connected, a hard disk on the primary master, and a CD-ROM drive on the secondary master.  A second hard drive must be placed on the primary EIDE channel's slave connector.  Additionally, you also must set jumpers on the disk drive itself to specify if it is to be a master or slave disk.  Jumper pins are used to detail the jumper setting that specifies how the drive is to be used.

 

Jumper Pin
jumpers
(Click to Enlarge)

Jumper Setting
jumpersetting
(Click to Enlarge)

A typical setup with four EIDE devices might look like this:
 
EIDE connection Unit
Primary Master Hard disk 1
Primary Slave Hard disk 2
Secondary Master CD-RW
Secondary Slave CD-ROM

SCSI

The SCSI (Small Computer System Interface) interface is typically found in high end systems and servers.  The main difference between SCSI and EIDE is that a single SCSI adapter can handle 7 or 15 devices, of varying types (internal or external hard disks, scanners, CD-ROMs, zip drives, etc.).  Another difference is that while most modern systems have their EIDE controller as part of the motherboard, SCSI controllers are often a separate expansion card.  SCSI drives are faster and generally more robust than EIDE drives.  The SCSI system holds its own computer power, thus freeing the CPU.


Hard Disk Upgrades

Hard disks have become progressively faster and cheaper, and with their increased capacity can hold ever-growing amounts of data.  Upgrading your hard disk is a common improvement you can make to your system, as is adding a second hard disk.  However, as drives get faster, they require improved cooling.  Many modern systems now come with multiple cooling fans to stop drives from overheating.  It is important to keep your system's cooling fans clean and dust-free, and to make sure they are running properly.

Keep a new hard disk in its electrostatic discharge protection container until you are ready to install it.   Handle hard disks carefully, and never handle more than one at a time.  Never stack them or place them on edge.  Avoid dropping a drive -- even a 1/4 inch drop can cause damage
Before you can physically install a new hard disk into your computer you must make sure that it is configured properly.  For an IDE drive this means specifying (using jumpers) whether it is a master or a slave device. 

There is no standard way to set jumper pins.  It varies across manufacturers, and even across different drives from a single manufacturer.  Consult your drive's documentation, or the manufacturer's web site for jumper setting configuration.  Many drives have the proper jumper settings printed directly on the drive itself.

 

Jumper Pin
jumpers
(Click to Enlarge)

Jumper Setting
jumpersetting
(Click to Enlarge)

For a SCSI drive, configuration entails setting the device's SCSI ID and the SCSI bus termination state.

Each device on the SCSI chain must have a unique SCSI ID.  On most systems the SCSI controller is set as the highest available ID (ID 7 on non-wide systems and ID 14 on wide and ultra-wide systems).  Typically the boot drive is set as 0.  Some SCSI controllers allow you to skip IDs (for example, you can have ID 0, ID 1 and ID 3), other controllers do not permit this.

If you are installing a new SCSI drive in a system that has other SCSI devices installed (for example, a scanner or a tape backup unit), terminate only the end devices on the SCSI chain.

SCSI ID Setting
scsisetting
(Click to Enlarge)

SCSI Termination
scsibus
(Click to Enlarge)

Use all four screws to securely mount your drive.  Using less than four screws may be tempting, but it may cause the drive to vibrate excessively and does not allow the case to absorb heat from the drive, and this can shorten its life.  Do not over tighten the screws, however, as this can warp the drive's internal frame.
After physically installing the drive you will need to configure it.  First, you will need to run FDISK in order to partition it, thereby defining areas of the disk for an operating system to use as a volume.  FDISK writes a master partition boot sector on the first sector of the hard disk.  This partitioning also prepares the drive for formatting, and tells the ROM BIOS which of the partitions are bootable.  If you are unfamiliar with FDISK, we encourage you to read  Using the FDISK Utility.
Second, you will need to format your disk.  There are two format procedures that are required prior to your using a new hard disk:
  • Low-level or physical formatting (LLF)
  • High-level or logical formatting (HLF)
When you format a floppy diskette, both types of formatting are done simultaneously, but on a hard disk they are separate procedures.  The LLF is performed by the manufacturer prior to sale, and for EIDE drives this is usually never done by the end user.  The low-level format writes the tracks and sectors on the disk.
The HLF is what is done by the DOS FORMAT command.  If you are unfamiliar with the DOS FORMAT command, we encourage you to read Using DOS FORMAT.  During the high-level format the operating system writes the structures required for managing data on the disk, basically creating a table of contents.

Hard Drive Problems

Your computer's hard drive holds your data, and so is an extremely important and valuable part of your computer.  Many things can go wrong with a hard drive -- some catastrophic, like total failure of the media (which can prevent your system from starting), while others are not catastrophic, but still serious, like sectors going bad (which can lead to the loss of a file or files).  For many of these problems the troubleshooting activities vary only slightly, depending on, for example, if your drive is receiving power or not.

Warning:  Anytime you do hard drive troubleshooting you take the risk of destroying any data on the drive.  It is always wise to attempt to backup any data prior to troubleshooting, if possible.  Never reformat or partition a hard drive except when all else fails, and always do regular backups of your data.
If you do not see any drive light or hear any drive activity and you see a message that the drive cannot be located:
  • Try booting from a boot diskette.  If you can, then the problem is with your hard drive.  Try switching to the C: drive.  If you can access it, you may have a boot sector problem.  You should check for a boot sector virus immediately.  If you can not access the drive, continue troubleshooting.
  • Make sure the 4-pin power connector is inserted securely into your drive.  If your drive is on a Y-connector make sure any other connections are secure.
  • Make sure the signal cable from the motherboard to the hard drive is securely seated.  Check for frayed edges or other damage to the cable.  If you have a spare, try replacing it.  If it is an EIDE cable, make sure that the red stripe that you see on one side of the cable is aligned properly with pin 1 on the disk.
  • Enter your CMOS Setup and confirm that the parameters for your hard drive (heads, cylinders, sectors per track, etc.) have been entered correctly.  In most modern systems these parameters are automatically detected, but you need to make sure that the drive is enabled in the CMOS Setup.
  • If you have a separate drive controller board (most modern systems do not unless they are SCSI systems) make sure it is seated securely in its expansion slot.
  • Try switching the non-working drive with a known, good, drive (remember you may need to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.  If it does not work as expected, you may need to replace the disk controller or the motherboard.

Power Cable
powercable
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Y-Connector
powery.jpgy
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Signal Connector
cables
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EIDE Cable
eide
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Pin 1
pin1.gif
(Click to Enlarge)

CMOS Setup
cmos
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If you see or hear drive activity (constant or intermittent) but your boot drive can not be located (you might see a "No Fixed Disk Present" error message on the monitor):
  • Check to make sure the signal cable is inserted with the proper orientation (that it is not reversed at one of the two ends).
  • Check that the signal cable is in good condition.
  • Check that your CMOS Setup has the correct parameters for the drive.  In most modern systems these parameters are automatically detected, but you need to make sure that the drive is enabled in Setup.
  • Boot from a boot floppy and attempt to access the drive.  If you can, it is likely that your boot files have become corrupt.  Check for boot sector viruses immediately.
  • Try switching the non-working drive with a known, good, drive (remember to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.  If it does not work as expected, you may need to replace the controller board.

EIDE Cable
eide
(Click to Enlarge)

CMOS Setup
cmos
(Click to Enlarge)

If you hear your disk spinning up but it is not recognized by your computer (you may get a "Hard-disk error" or "Hard-disk controller failure" message on your monitor):
  • Check to make sure the signal cable is inserted with the proper orientation (that it is not reversed at one of the two ends).
  • Check that the signal cable is in good condition.
  • Check that the jumpers are set correctly on your drive(s) and that the primary is set as primary, and the secondary or slave, if existent, is set as secondary.
  • Check that your CMOS Setup has the correct parameters for the drive.  In most modern systems these parameters are automatically detected, but you need to make sure that the drive is enabled in Setup.
  • Boot from a boot floppy and run FDISK to confirm that there is at least one DOS partition and that if it is your boot drive, that it is active and bootable.
  • Boot from a boot floppy and attempt to access the drive.  If you can, it is likely that your boot files have become corrupt.  Check for boot sector viruses immediately.
  • Try switching the non-working drive with a known, good, drive (remember to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.  If it does not work as expected, you may need to replace the disk controller or the motherboard.

EIDE Cable
eide
(Click to Enlarge)

Jumper Pin
jumpers
(Click to Enlarge)

CMOS Setup
cmos
(Click to Enlarge)

If you hear your drive spinning up at start-up but then it immediately spins down:
  • Check to make sure the signal cable is inserted with the proper orientation (that it is not reversed at one of the two ends).
  • Check that the signal cable is in good condition.
  • Check that the jumpers are set correctly on your drive(s) and that the primary drive is set as master, and the secondary or slave, if existent, is set as slave.
  • Try switching the non-working drive with a known, good, drive (remember to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.  If it does not work as expected, you may need to replace the disk controller or the motherboard.

EIDE Cable
eide
(Click to Enlarge)

Jumper Pin
jumpers
(Click to Enlarge)

If your drive light remains on continuously but the drive is not accessible:
  • The boot drive can not be located.  Check to see that the signal cable is inserted with the proper orientation (that it is not reversed at one of the two ends).
  • Replace the drive with a known, good, drive (remember to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.  If it does not work as expected, you may need to replace the disk controller or the motherboard.

EIDE Cable
eide
(Click to Enlarge)

If your drive spins up when power is applied, but then rapidly spins down again:
  • Make sure the 4-pin power connector is inserted securely into your drive.  If your drive is on a Y-connector make sure any other connections are secure.
  • Make sure the signal cable from the motherboard to the hard drive is securely seated.  Check for frayed edges or other damage to the cable.  If it is an EIDE cable, make sure that the red stripe that you see on one side of the cable is aligned properly with pin 1 on the disk.
  • Try a new signal cable.
  • Check that the jumpers are set correctly on your drive(s) and that the primary drive is set as master, and the secondary or slave, if existent, is set as slave.
  • Replace the drive with a known, good, drive (remember to change the CMOS Setup settings if you do this).  If the good drive works as you expected, then the replaced drive is bad.

Power Cable
powercable
(Click to Enlarge)

Y-Connector
powery
(Click to Enlarge)

EIDE Cable
eide
(Click to Enlarge)

Jumper Pin
jumpers.jpg (35924 bytes)
(Click to Enlarge)

If, after completing the installation process for a SCSI drive, the drive's LED does not show on/off activity when the host is trying to communicate with the drive:
  • A duplicate SCSI ID setting may be the problem.  If this is the case, change the ID so that each device on the SCSI chain has its own unique ID.
  • If the SCSI IDs are all unique, make sure that your SCSI chain is terminated properly.

SCSI ID Setting
scsisetting
(Click to Enlarge)

SCSI Termination
scsibus
(Click to Enlarge)

If you see a "Sector not found" error message on your computer monitor you likely have a non-catastrophic media problem with your hard drive, mostly likely some sectors are going bad.  This commonly happens to older drives:
  • Use a disk utility to evaluate the drive and then locate and map out any bad sectors.
  • If you have a large number of bad sectors, you might consider getting a low-level format utility from your drive manufacturer, backing up your drive, doing a low-level format, and then reformatting and restoring your drive.  This may help you to recover some of the bad sectors.
If you suspect that your boot sector has been corrupted or destroyed, and that this has not been caused by a virus, you should try running FDISK with the /MBR parameter.  This command will replace your master boot record without altering the partition table at the end of the sector.
If running FDISK /MBR does not work, you will need to run a full FDISK and then DOS FORMAT on your drive.  This is a drastic step and will destroy the data on your hard disk.  Before you do so, you can boot off of a start-up floppy and try to backup any critical data that may not be on your most recent system backup.  If you are unfamiliar with configuring your hard disk, we encourage you to read Configuring a Hard Disk.
If your computer fails to load the operating system on a cold boot, but seems fine when you do a reset (warm boot):
  • It is possible that your hard drive is not powering up in time for the cold boot to execute properly.  Check your CMOS Setup and make sure the POST has not been disabled.  If it has, the lack of the RAM test may be giving your disk inadequate time to spin up before the operating system is loaded.
  • Your CMOS Setup may give you an option to enable or disable the "Quick" POST.  Make sure you are running the full POST (as opposed to the quick).  This longer POST includes a more in-depth memory test, and may provide your disk sufficient time to spin up before the operating system is loaded.
  • Alternatively, your CMOS may have a Power On Delay/Boot Delay option that will allow you to specify a time in seconds to delay the boot process.  This is usually disabled, and should be unless you are experiencing this problem.

CMOS Setup
cmos
(Click to Enlarge)

Quick POST
quickpost
(Click to Enlarge)

Your hard drive's performance seems to be degrading over time, getting slower and slower.
  • Boot from a boot floppy and make sure there are no drivers or Terminate but Stay Resident (TSR) programs being loaded.
  • Check for viruses.
  • Run a Windows defragmentation utility.

Data Recovery Solutions

Data loss can be one of the most terrible things that can happen to a computer user.  It often happens at the worst possible time -- you're up against a deadline and you've been working for hours when suddenly your computer crashes and everything you've been working on is lost.

Data recovery is the process of retrieving computer data that, for any number of reasons including hardware failure, software failure or computer viruses, has become inaccessible using normal methods.

If you cannot recover your data and it is very important and valuable to you, there are commercial "data recovery houses" available that can provide data recovery solutions including in-lab and remote services, as well as some cost-effective do-it-yourself software.

Data Loss
driveprob
(Click to Enlarge)

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Disclaimer:  These pages are provided for information purposes only.  We cannot be held responsible for any damage you might inflict on your system while using the information contained herein.  We recommend you always refer any technical matter that is "over your head" to a qualified computer technician.
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2011 Double-Hammer Computer Services.  All rights reserved.
Last Updated: September 04, 2011

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