Like all electromechanical equipment, the hard drive one time has a shelf life. Also, the HD is susceptible to problems related to the type of use, manufacturing defects, accommodation and handling, power management etc.
The old hard drives were much more problematic than modern. Added to this, it was still necessary to perform complex procedures to put them into operation. Until the 80s it was essential to do a low level format these devices, to demarcate the physical spaces where the sectors and tracks would be located before the partitioning and operating system installation. Put an old HD in production was a chore.
With the advent of the popularity and easy access to computers in the habit of storing information on paper was largely replaced by digital storage containers. This change has brought convenience, savings and better data management. With this, the demand for solutions for recovering damaged hd rose abruptly.
Operation HD
There are several articles in the Hardware Guide that explain, in detail, as an HD works. Either way, we will consider some important points.
The main components of a hard drive are the disk controller (popularly known as logic board), read heads, motor and magnetic media (plates).
The disk controller (disk controller) is responsible for managing low-level operations such as engine operation, movement of the head and the transmission of data to the host controller (host controller or host bus adapter), which interprets this information and delivery to the processor or memory. Too often people confuse the disk controller to the host controller. Are devices with different functions. The disk controller is connected directly to HD, while the host controller is connected directly to the motherboard.
The heads, also known as reading heads are responsible for storing and reading data on the plates. They act as small magnets attached at the end of the HD arms, effecting transactions through the magnetic poles along the alignment of dishes. The result is the famous bits 1 and 0, which will later be transformed into readable data.
The engines are responsible for turning the dishes in a certain rotation and create an air mattress that will allow read heads "float" on the magnetic media.
The plates are disk-shaped component, which contains a magnetic layer where the data is properly stored. They are divided into sectors, tracks and cylinders. As the read heads, the dishes are sensitive to any kind of friction or impact.
A sector is the smallest physical hard disk drive and its size can be 512 or 4096 bytes. The trails are formed by a set of sectors and cylinders are formed by a set of tracks. All this occurs in logical organization level.
Common Problems
The main cause of malfunction on a hard drive are the heads and dishes. These components work intensely at all times and suffer from wear that will shift the internal air to high temperatures.
A defective motor can also compromise the functioning of the hard drive. Although it is more complicated to be solved, the same problem occurs infrequently.
Unlike that discloses internet besides the logic board is among the lowest of troublemakers. Are often mistaken for modules, heads or motor.
During its operation, especially in moments of intense reading and writing, the storage device must remain static without suffering any outside action. At this point, falls, slaps, strokes etc, however small, will damage the HD.
What can not be done.
To become a successful professional in the field of recovery in HD many years of study, with emphasis on the operation of the storage devices, file systems, computer forensics, electronic etc. are needed Also must acquire (and know how to operate) imported special equipment, whose value is often quite high.
One must understand that computer maintenance is different from recovery HD. However, in recent years many computer technicians began to "venture" in the field of data recovery. To make matters worse, there were some dubious "courses" of recovery in HD without recognition from reliable institutions (MEC, for example) and with very low workloads, attempting to market dozens of pseudo professionals every month.
With the market full of untrained technicians, it is common to come across the most bizarre and destructive "methods" of "recovery" on hard drives. Below are some examples.
As many already know, a hard disk must be opened for repair in an extremely clean room, known as Class 100, or a structure that emulates this environment. Some "professionals" believe they can replicate this environment in a bathroom, through the belief that the steam from a shower running for a specified time may sanitize the site, creating an environment conducive to opening the device.
It has long circulated on the internet the information that a HD could come back to life after spending a few hours in a freezer. Exist today supporters of the practice. They believe that low temperatures minimize faults in magnetic media. It does not have scientific proof, this procedure may cause moisture inside the machine because, contrary to what many think, the hard drives are not sealed vacuum.
A practice that seems to be consistent, but that brings more problems than solutions, is the famous exchange logic board. This method is common among inexperienced professionals that exchange without even knowing if it is the cause of the malfunction on the hard disk. However, they ignore the fact that even in identical models, each HD has its own data allocation, as well as the alignment of heads and tables mappings bad sectors, known as P-List and G-List. In practice, the HD receiving the new logic board is not enough even to be recognized by basic (BIOS / UEFI) systems. Even when they are detected, the controller will probably force the damaged hard drive to work as if it were your original HD, could result in permanent data loss.
A defective hard drive must be opened only in the last instance. This procedure involves risks and should be practiced only by skilled and experienced people. It is the trump card of good professionals. However, there are - even some old companies - professionals who violate the seal of HD to perform a simple diagnosis. This is a grotesque procedure that may jeopardize the client's data.
Another common mistake committed by many computer technicians, is to submit a problematic HD programs that perform a lot of reading and writing operations. The fact is that there are no programs that fix hard drives, or blocks or sectors. Applications that promise such a feat, only the dishes on track for bad sectors forcing the controller to remap them. Containing the same data, bad sectors are exchanged for new ones. From there begins the loss of data. Moreover, these programs cause unnecessary stress on an already compromised device. Not infrequently the HD stop in the middle of the process.
There are many other harmful to hard drives that would fit procedures not listed here, and many of these can be avoided by using only common sense.
What Can Be Done
One must keep in mind that the common user or computer technician have few options when hard drives have problems. When you become aware that the hard drive is faulty it is recommended the immediate replacement or seeking professional assistance through a specialized company. However, there are safer ways to test the health of a drive.
The principle of diagnosis in hard disk is to be the least invasive as possible, causing minimal stress on the equipment. Therefore, one should avoid scans sectors or blocks, and you should not turn on / off the HD more than 1 or 2 times.
From the moment that you lose access to the data, the first step is to check if the hard drive is detected by the base system (BIOS / UEFI) and the time that it takes to be identified. A HD that is not recognized or it takes to be detected is damaged. In some cases, the type of damage can make the BIOS crashes or restart the computer.
One should be attentive to the warnings displayed by the basic systems. Messaging system not found, boot failure, disk not found errors and SMART is a bad sign. The operating system can also report these problems. Some stop errors shown in the famous blue Windows screens may indicate problems in the HDD. On Linux systems, these types of errors will be generated in the / var / log / syslog or / var / log / messages.
SMART is a great ally of users and technicians. This technology is characterized by a set of internal routines in HD himself who report their condition. Programs like GSmartControl (Linux / Unix) and the HD Tune (Windows) can interpret the SMART logs, showing details about the status of the hard disk. Thus, one can discover the status of a hard drive, safely, without scanning.
Abrupt shutdowns computer - power outage, for example - can cause problems on hard disks, especially when data transfer is taking place. However, the most common is that only the file system is affected. This is because the journal (records containing changes implemented in file systems) was not properly updated. This type of problem can be solved with system integrity checkers such as CHKDSK (Windows) and Fsck (Linux). But before using these programs you need to make sure that the HD has no physical problems.
The procedures described here are sufficient to discover for defects on a hard drive. Obviously, nothing prevents "experiments" are performed when no important data in question. It depends what you want to do with HD.
conclusion
There are products that should be changed when they have problems such as lamps, lighters, etc. taps Unfortunately, the hard disk is one of them.
The term "Recovery HD" is widely used by lay people who need solutions to recover files on a hard drive that is inaccessible. Repair, literally, is impractical and virtually does not exist. Moreover, such a procedure is not advised, based on practices consistent computational storage.
The good news is that there are companies specializing in recovering information from hard drives that are damaged. Many of them use the term "Recovery HD" on their websites as reference to rescue data in defective hard disks. This makes life easier for lay users searching for this type of solution on the internet.
Modern hard drives store a large amount of information in a small space, or high density is possess. You need to be very careful with these devices because a small damage can affect a large volume of data.
The era of HD is coming to an end. Gradually, the hard disk space will the SSD (solid state disk), which uses chips instead of magnetic disks. Anyway, many of the concepts of diagnosis and recovery HDDs can be applied to SSDs.
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