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Hard disk drive is one of the most basic subsystems of a computer since all our information is stored there. As it is known, it consists of mechanical parts and develops due to the temperature and the friction of its mechanical parts during its use, gradual problems that have to do mainly with the fidelity of writing and reading data in its fields.
Chronology
Until 1957, data was stored on tapes. .
This disc cost $ 35,000 a year to rent (IBM did not sell this disc) and was twice the size of a refrigerator. this technology was developed in Winchester, England) and had two sides each of which could store 3030 MB. Later the boards were made with a diameter of 30 "and 14". They were installed in towers, which contained dozens of these magnetic boards.
In the early years of computer development, low-cost floppy disks were the most popular storage media, but with IBM XT in 1983-84, hard disks became the preferred storage medium. The first hard drives were large units (5.25 "in diameter). Since then, the growth and development of hard drives has been amazing. Modern hard drives are 3.5" in diameter and of course, they are also available in much smaller sizes.
Properties
Hard disk drive is a magnetic storage medium used mainly in computers in digital camcorders, portable mp3 players, gaming machines and many other electronic constructions, its capacity is measured in GigaBytes. There are hard drives on the market that can store many Giga Bytes with the prospect of improving in terms of speed and storage capacity (capacity). The advantage of a hard drive is the ability to store large amounts of information. Hard disks are used in computers to store data, especially programs and files that need to be maintained, as opposed to RAM where data is erased when a power outage occurs.
Technology
The hard disk consists of: magnetic disks made of metal or plastic and coated with a thin layer of iron oxide or other magnetic material, the axis of motion of which the magnetic disks rotate at the same speed as the read / write heads on arms above and below each disk surface, moving back and forth. The combination of the movement of the arms with the movement of the discs, allow the heads to have access to all points of the discs.
electronic components that serve the operation of the hard disk, communicating with the computer and undertaking the movement of heads and data transfer. Hard disk data is stored in the form of tiny areas magnetized in different directions. The disk read head must recognize these differences and record them as "0" and "1" of the digital information. The problem is that as magnetized areas become smaller, their differences become less and less difficult and difficult to read.
Interface
The main computer hard drive is denoted by the letter 'C:'. There may be more than one hard disk in a PC or we can even split one hard disk into two or more partitions and store different data in each partition, e.g. in one section the various programs and in the other information resulting from data processing.
In this case the next hard disks, except the basic 'C:', are symbolized by the following letters (after C) of the Latin alphabet, ie D, E, etc. In PCs, hard drives are interconnected in a separate corridor called first the IDE corridor and then the EIDE (Enhanced IDE). In the EIDE corridor up to four devices are interconnected, mainly disks and CD-ROMs. In essence the corridor consists of two channels, in each of which 2 devices are interconnected.
Zeus of the two precedes the control of the channel and is called master, while the other is called slave. This distinction allows slow (CDROM) and fast (hard drives) devices to coexist on the same channel. The biggest advantage of this model is the simplicity of its implementation that allows manufacturers e.g. hard disks to integrate many of the IDE adapter electronics onto the disk and finally the format of the IDE adapter in the PCI bus is very simple. The SCSI bus model comes from the host space and offers sophisticated EIDE features. This form of bus allows you to connect multiple peripherals, mainly hard drives and CDROMs.
Of course it is possible to connect other devices that follow the same standard, such as scanners, backup devices and others. An SCSI adapter is required to connect the SCSI bus to an I / O bus (eg PCI). Up to 7 devices can be connected to this corridor, each of which has a separate SCSI address. SCSI speeds range from 5MB / sec in normal mode, 10MB / sec in Fast SCSI, 20MB / sec in Ultra (Fast-Wide) -SCSI and 40MB / sec in Ultra-Wide SCSI. Of course, this protocol has also been developed and nowadays there are hard drives with a transfer speed of 320 Mbytes / sec. This speed is of course the maximum possible bus speed, and does not refer to the actual communication speed of the peripherals which can be much lower.
The SCSI standard is much more reliable and faster than the IDE, but the wide variety of categories and implementations, until recently, prevented its spread in the PC category.
Nowadays there is a plethora of SCSI peripherals for PCs coexisting with the EIDE bus standard. SERVER systems. PCMCIA is a relatively new corridor standard for laptops. The PCMCIA corridor connects any kind of peripheral that is in the form of a card. So there are network cards, memory cards, fax / modem cards and even EIDE disks that are the size of a thick credit card. PCMCIA cards are lightweight, small in size, easily connected and disconnected from the aisle, allowing a laptop to have a variety of peripherals without increasing its weight.
For some years now, another class of hard drives based on the S-ATA Serial Advanced Technology Attachment standard has been introduced, which is evolving rapidly, having been largely marginalized (putting in a few years essentially in the history closet). Used to transfer data from hard disks or optical data storage to the central processing unit. It is slowly replacing the classic IDE bus. Unlike IDE (Integrated Drive Electronics) it transfers data serially instead of in parallel.
This gives the advantage of less wiring and simpler design compared to traditional 40-end cable ties, it uses only 7 cables. This allows better ventilation of the computer case and better avoidance of electromagnetic interference. SATA sockets are easier to use and prevent misplacement. Data transfer requires less energy, which is ideal for laptops. SATA devices in addition to different cable ties also need different power sockets due to different voltage requirements and for ease of use. The speed of SATA is 150 Mbit / s and of SATA 2 is 300 Mbit / s. The story of its evolution is currently ending with the relatively new discovery of technology SSDs, which seem to have taken over the work of classic hard drives. SSDs are essentially flash drives (what are usb sticks like? Something like that but nothing to do with usb flash memory speeds).
Problems-Disadvantages
Η The recording and reading from the heads of the hard disk is done while it rotates at high speed and is magnetic, ie the read-write heads do not come into contact with the magnetic material where the data is written. However, because the distance between the heads and the magnetic material of the disk is very small, it is very likely from misuse but also due to the physical wear of the mechanical parts at some point to create Bad sectors. The appearance of Bad sectors usually marks the impending death of the hard drive and it is completely useless to try to keep in ΄΄life΄΄ a hard drive that is now predetermined and certain its death.
However, before we get to how we can repair damaged sectors, we should note that a very basic rule for the long survival of a hard drive is how we treat it. For example, for a hard drive that works long hours at high temperatures, you greatly reduce the life expectancy set by the manufacturer, which generally depends on the drive, thousands of hours of work.
A damaged or faulty disk on our computer is a potential βόTime bomb΄΄ for our computer in the sense that we risk losing all our data at any time other than the various problems that may occur (unexplained crashes, sudden restarts). etc.). However, you should know the average lifespan of a disc ranges from about 3-5 years depending on its use and build quality. A very good overview (which you should have) for diagnosing and predicting potential problems is The HDDScan.
It is a free hard disk diagnostics software (RAID array servers, USB Flash drives and SSDs supported). The program can check the storage device for errors (problem areas), shows SMART features and can change some hard disk parameters, such as AAM, APM, etc. HDDScan can be used to perform regular "health check" checks on your drive and predict downtime so you can prevent data loss and back up your files.
However, before we get to how we can repair damaged sectors, we should note that a very basic rule for the long survival of a hard drive is how we treat it. For example, for a hard drive that works long hours at high temperatures, you greatly reduce the life expectancy set by the manufacturer, which generally depends on the drive, thousands of hours of work.
A damaged or faulty disk on our computer is a potential βόTime bomb΄΄ for our computer in the sense that we risk losing all our data at any time other than the various problems that may occur (unexplained crashes, sudden restarts). etc.). However, you should know the average lifespan of a disc ranges from about 3-5 years depending on its use and build quality. A very good overview (which you should have) for diagnosing and predicting potential problems is The HDDScan.
It is a free hard disk diagnostics software (RAID array servers, USB Flash drives and SSDs supported). The program can check the storage device for errors (problem areas), shows SMART features and can change some hard disk parameters, such as AAM, APM, etc. HDDScan can be used to perform regular "health check" checks on your drive and predict downtime so you can prevent data loss and back up your files.
Repair programs
Of course there are programs that can fix the damaged sectors on our hard drive but the very good ones (professional specifications) are very expensive and for the average use it is a free gift as it will cost him less to buy a new hard drive than to repair it. Be aware that Bad Sectors repair is not a panacea that guarantees a complete repair of the problem but may be a temporary and necessary action to take to save our data and transfer it to someone new. hard drive that we should definitely buy.
There are several free programs with which we can find out if our hard drive has damaged sectors but almost no free ones to repair them with absolute reliability. (In fact, no repair is done, just mark the allocation table of the disk so that they are not used again). Therefore the golden rule for keeping hard drives alive as long as possible is the least possible strain (read, write, low, drop, beats, high temperatures (the temperature of the hard drive should not exceed 50- during operation 55 degrees Celsius).
The appearance of bad sectors can come from either a power outage during recording or from some other hard drive malfunction for some other reason such as a fall, mechanical failure and more. The question is: Can the bad sectors be repaired? NOT always, however, if the data stored in the domain is just invalid, but your hard drive is working properly, you can repair the bad sectors that have been created.
Free applications
One of the best and most reliable free programs to see if your hard drive has Bad sectors is Disk Scanner with the help of which you can thoroughly examine your hard drive for problems. The application does not need to be installed and can run on all windows. Some other free diagnostic programs that I could single out are HDDScan, the Windows Surface Scanner, and the Macrorit Disk Scanner .
If you find problems with your hard drive there are programs to fix it until you buy another one and transfer its data. Unfortunately, the free applications for troubleshooting bad sectors are very few, measured in fingers and their effectiveness usually comes naturally after their use. Also, one of the best programs to deal with these situations and not only is HDAT2.
This is a completely free application that works just like the previous one as a floppy disk or CD and you can use it to diagnose and fix various problems on your hard drive. (ATAPI / SATA, SSD and SCSI / USB devices.) With the difference that you will need to make a DOS boot diskette or a copy of it on a CD / DVD and boot your system. The program operates in a Dos environment and despite its advantages it has a degree of difficulty for users who are unfamiliar with this environment.
