Reasons For Data Loss From Computer Hard Disks

Introduction

The last 20 years has brought about a proliferation of computer use in society. Technology is in a constant state of evolution and computer based activities are becoming increasingly integrated with their users’ lives. A number of years ago, it was unthought-of to conduct activities such as banking and shopping online. In addition to this, the vast communication possibilities that are now in existence are making the world a smaller place as people are using a multitude of messaging services such as MSN to stay in contact. The benefits of these highly sophisticated technologies are however, faced by numerous threats. Computers are, more than ever susceptible to malicious use in the forms of hackers, viruses and fraudulent activity. One of the reasons for this is that computers are responsible for storing large amounts of information. Aside from threats posed by malicious use, computers also face a number of issues from an architectural perspective. The vast majority of data stored on a computer is saved on the hard drive and although improvements are continuously being made in terms of their size and capacity, hard drives are always vulnerable to a great deal of stress. In turn, hard drives inevitably have a shelf life of approximately three years. A study conducted by the accounting firm McGladrey and Pullen estimates that one out of every 500 data centres will experience a severe computer disaster this year. As a result, almost of half those companies will go out of business (Peddle 2006).

The objective of this essay is to summarise the main ways in which hard drives can fail, thus incurring a loss of data or difficulty in accessibility. The essay is structured as follows; the first section provides a description of the main ways in which hard drives can fail, along with the effect that this has on the stored data. This is followed by a description of the methods that can be conducted in attempt to try and prevent failure as much as possible and culminating with a brief conclusion and summary of the essay.

Causes of failure A hard disk drive is a digitally encoded non-volatile storage device which stores data on rapidly rotating disks with magnetic surfaces called hard disk platters (Wikipedia 2006). The read-write heads of the hard disk are used to recode and retrieve the data stored on the hard disk as the disk platter rotates at a very high speed. Hard disks operate under extreme stress and will eventually fail due to general wear and tear accrued through age or some form of malfunction or failure. The chances of failure of a hard drive therefore increase greatly over time and ironically the chances are greatly increased as hard disks improve and develop. The phenomenon of hard disk failure is raising higher and higher; as to increase the read and write speed, today we have the latest hard disk rotating amazingly faster and this immense revolving speed generates massive centrifugal force, a single adverse cause in the course of normal operation can cause severe hard disk failure (Bista 2006).

Hard disk failures can be generally classified in two categories, namely physical and logical failures. Physical hard disk failures are the type of failures in which something is physically wrong with the hard drive itself and symptoms may include a grinding or clicking sound (Posey 2006). A logical failure is the type of failure in which there is nothing physically wrong with the drive itself however, the information stored on the hard disk is in bad shape. Normally this type of failure can be repaired by using a tool such as Scan Disk (Posey 2006).

The following section outlines the main cause of hard drive failure which are as follows:
• Firmware corruption
• Electronic failure
• Mechanical failure i.e. head crash
• Circuit board malfunction
• Logical errors
• Human error

Types of hard disk failure Firmware corruption Firmware is the software code that controls and is embedded in the physical hard drive hardware (Data clinic 2006). It is responsible for the operations of the hard drive and its activities include configuration, management of the interaction that takes place between the other components and the safe powering on/off of the system. At start-up, a hard disk loads the service data from its firmware zone into RAM and then allows the drive to report on readiness. If there is damage to these modules, then the drive will report either it’s family identity or will not detect it at all (Disklabs 2006).

In the event of such an occurrence, the computer will be prevented from accessing any data on the hard disk. The benefit to this is that it is merely an accessibility problem and a firmware failure does not automatically incur a data loss. Once the drive has been repaired, it is possible to recover the data.

Electronic failure Data clinic (2006) describes how electronic failure usually relates to problems on the controller board of the actual hard disk. This may be due to the computer actually suffering a power spike or electrical surge that knocks out the controller board on the hard disk making it undetectable to the BIOS. This means that whilst there is an electronic failure, any data stored on the hard drive will be inaccessible until the problem is fixed. The nature of this type of problem however, is advantageous as it is a mere hindrance and data will not be lost or corrupted and is therefore fully recoverable. Mechanical failure Mechanical failure is generally considered to be more serious than electronic failure or firmware corruption as it often leads to data loss and even complete data loss if prompt action is not taken. There are numerous types of mechanical failure; these can range from motor problems to one of the most common types of known failures is a head crash. A head crash, as it’s name implies, occurs when the read-write heads of the hard disk collide with the disk’s rotating platter surface (Data clinic 2006). Often, this can cause damage to both the heads and even the hard disk itself.

The head normally rides on a thin film of moving air which is entrapped at the surface of the platter (Wikipedia 2006). The platter is coated with a magnetic layer and a crash can occur if a small amount of dust, a sudden movement of the computer or power surge causes the head to bounce against the disk and damaging the magnetic coating. Modern A head crash, as its name implies, occurs when the read-write heads of the hard disk collide with the disks rotating platter surface (Data clinic 2006). Often, this can cause damage to both the heads and even the hard disk itself.

The head normally rides on a thin film of moving air which is entrapped at the surface of the platter (Wikipedia 2006) The platter is coated with a magnetic layer and a crash can occur if a small amount of dust, a sudden movement of the computer or power surge causes the head to bounce against the disk and damaging its magnetic coating. Modern drives spin at extremely high speeds (between 5, 00 and 15,000 rpm, (Wikipedia 2006)) which means that when such a collision occurs, the damage incurred can be quite serious.

Obviously, data corruption will occur at the onset of a head crash as it will then become unreadable when the read-write head attempts to access it. Furthermore, once a head crash has occurred, this increases the probability of future head crashes, especially if there is dust in the system, for instance which means the user needs to take prompt action to rectify this in order to prevent further head crashes and risk losing all data stored on the hard disk.

Circuit Board Malfunction The circuit board is responsible for powering and controlling the mechanical unit. It is exposed to variations in temperature and as a result, the chips that comprise the circuit board surface can develop small breaks internally which can cause circuit interruption and electrical failure. Furthermore, the failure of any of the other electrical components of the computer can result in a defective circuit board, thus causing the hard drive to fail and data access is then prevented.

Logical errors Logical errors also differ from the other failures mentioned as it usually means that there is nothing actually physically wrong with the disk in terms of architectural faults, instead there is a problem with the information stored on it. There could be an invalid entry in a file allocation table for instance (Data clinic 2006). Logical errors are not too serious, unlike mechanical failures and can be tackled with various software tools. Caution should however be extended because if a fix utility is run inappropriately on the hard disk, the stored data can often become unrecoverable. Human error

In a sense it is rare that a hard disk failure could be caused by a human alone. That is, of course providing that users take caution in how they handle a computer. Combined with mechanical failure, human error accounts for almost 75% of all incidents of data loss (Peddle 2006). All of the previously mentioned hard disk failures could be caused by computer misuse on the user’s part. Computers are very sensitive to changes in temperature, dust and dirt etc entering the hard drive, electrical power surges and knocks and bumps which may occur. Users should therefore take extreme caution to prevent any of these circumstances from occurring as much as they possibly can.

Other problems not caused by the hard disk Aside from problems that may occur within the hard drive itself or damage that may be incurred on the users’ part, other failures can occur in other parts of the computer which can have a knock on effect to the performance of the hard disk. These problems include IDE cable malfunction, power connector problems and inappropriate BIOS configuration. Each of these problems is explained below.

• IDE cable malfunction IDE flat ribbon cables are notoriously known to cause trouble. Often these cables can turn defective without any necessary poor treatment from the user. It is therefore a good idea to check the IDE cable if any problems seem apparent with the hard drive.
• Power connector problems If the power connector is of a poor quality, this could mean that the hard disk is not powered properly or interruptions occur. Again, this can be easily rectified when problems seem apparent in the hard disk by trying out a different power connector of a higher quality.
• Inappropriate BIOS configuration