How to check a hard drive for bad sectors. Bad sectors or bad blocks

In this article we will talk about recovering bad sectors of a hard drive and the reasons for their occurrence. Step-by-step instructions will help you prepare for this procedure and cope with it yourself.

What are bad sectors?

Let's take a quick look at the structure of the hard drive. It consists of several separate disks, above which there are magnetic heads designed for reading and writing information. When storing data, the heads magnetize certain areas of the disk, which is divided into tracks and smaller components - sectors. It is in them that units of information are stored. If a sector becomes unreadable, it is called “broken”.

Several signs indicate the occurrence of such a problem:

squeaks, rattles, tapping when the disk is operating;
heating the surface of the HDD (this should not happen under normal conditions);
common errors when working and starting the operating system.

Typical reasons

The main reasons for the appearance of broken hard drive segments are:

Also, malfunctions in the hard drive may occur due to mechanical damage. They are often caused by dropping a hard drive or computer, resulting in damage to the magnetic surface (for example, during transportation). Non-working parts also appear due to manufacturing defects. In this case, they may not appear immediately, but “crumble” over time, quickly increasing their number to a critical level.

Important! If you suspect mechanical damage or defects, you should immediately contact specialists or exchange the hard drive under warranty.

Recovering bad HDD sectors using Victoria

If the appearance of broken segments is associated with software failures, then they can be restored using specialized software. One such program for recovering bad hdd sectors is Victoria. The utility is available in two versions - for Windows and DOS. Recovery via DOS will be the most effective, since when the OS is running, some sectors may be occupied and therefore unavailable for scanning.

Victoria HDD - diagnostic program

Scanning

To get started, we will need to do a little preparation. First, you will need a disk with a program image recorded on it or a bootable USB flash drive. If everyone can cope with recording an image, then creating a flash drive may be difficult.

Let's take a closer look at this step:

Note! The program takes up very little space, so after installing it, the drive can be used to store other information. To avoid accidentally deleting files necessary for the utility to work, it is recommended to select a separate folder for them.

Let's start the scanning process:

Here we need a point "Reallocated sector count", which displays the number of fragments located in the reserve zone, as well as "Current pending sectors", where parts that cannot be read are displayed. If their number is not very high, then the disk can be restored.

Hard drive recovery

Let's figure out exactly how this process happens. Problem segments can be roughly divided into two types. The first ones are not readable due to a mismatch between the information stored in them and its checksums.

This error occurs during a power outage, when new data has already been written, but the checksums remain old. They simply cease to be recognized and are restored quite easily - by formatting them and recording the correct amounts.

The second type occurs as a result of mechanical damage. In this case, recovery is more difficult, but still possible. Restoring the functionality of such parts is carried out through the use of reserve areas that are on each hard drive.

We begin to recover each of these types of errors.

Video: HDD - “healing” bad sectors

First, let's try to fix bad sectors by erasing the information stored in them:

press F4 and get to the verification menu;
in the menu for selecting operations with unreadable sectors, indicate “BB: Erase 256 sect” and press “Enter”.

A long process of scanning and repairing bad sectors of the HDD will begin. If the program finds a bad sector, it will try to erase it, thereby correcting the error. If a mechanical defect is present, an error will be reported. In any case, you must wait until the check is completed and then separately correct the sectors with physical defects.

For this:

Now the recovery operation will work on a different principle, trying not to erase bad sectors, but to replace them with space from the reserve area.

Important! If there are a lot of such sectors, then the reserve space may run out. A special message will inform you about this, and further restoration will become impossible.

After successfully recovering bad sectors on your hard drive, it is recommended to conduct a full check of the file system for errors.

This can be done using the CHKDSK utility or in the following way:

Photo: checking the disk for errors

Attention! To ensure that the system not only finds, but also corrects problems, before starting the scan, select “Automatically fix system errors.”

The methods described above will help you easily deal with non-critical cases of problem sectors, find and fix them. By following our instructions exactly, any user can do this on their own, even without computer education. We hope that this information was useful to you.

Over time, bad sectors appear on any HDD that are unreadable. When the number of bad blocks exceeds all permissible limits, the hard drive refuses to work. However, under certain conditions, the hard drive can be cured using special software.

What are bad blocks?

HDD (hard disk) consists of several magnetic disks, above which there is a head that writes and reads information. The surface of the drive is divided into tracks and sectors (the smallest division unit). If information is not read from a certain sector, then it is: bad, faulty, broken or simply a bad block.

Restoring bad sectors is not an easy task, but it can be done. If there are few bad blocks on the HDD, you can cure the disk, while simultaneously extending its service life.

The very presence of bad sectors is a bad sign, so even after repair you cannot use the HDD for a long time - it can fail at any time.

Working with VictoriaHDD

VictoriaHDD is one of the most famous programs for hard drive treatment. It is distributed under a free license and allows you to fix bad blocks in DOS mode. However, working with it requires some preparation.

Creating a bootable USB flash drive and setting up the BIOS

Download the ISO image of the VictoriaHDD utility and write it to a flash drive using WinSetupFromUSB.

Open WinSetupFromUSB and select the connected flash drive.
Check "Auto format", select "FAT32".
Specify the LinuxISO/otherGrub system and click the button on the right. Using Explorer, show the path to the downloaded ISO image, click “Go” to start recording.
After creating the Victoria bootable media, you need to restart your computer and open the BIOS. In the “Main” section there is an item “SATA Mode” - you need to set it to “IDE”, because in the “AHCI Mode” Victoria does not recognize the connected drive. Press F10 to exit the BIOS and save the changes.

After completing all the preparations, restart your computer again. When starting, start pressing F11 so that the boot menu appears. Select the bootable Victoria flash drive to run the program in DOS mode.

Recovery and follow-up

To restore, do the following::

After launch, press “P” (English keyboard) to bring up the “Select Port” menu. If the hard drive is connected via the SATA interface, select the “Ext. PCI ATA/SATA". For hard drives connected via IDE, you need to select the appropriate port.
A list of channels will appear, each of which has a number. Look at the number for your drive and enter it in the field below.
Press F9 to open the SMART table. Study two items: “Reallocated sector count” and “Current pending sectors”. The first line indicates the sectors transferred to the reserve zone; in the second - places from which information cannot be read (bad blocks). If there are only a few bad sectors, try restoring them.
Press F4 and launch “BB: Erase 256 sect” mode. If during the analysis the program finds a bad block, it will try to fix it. If the sector is not physically damaged, then Victoria will heal it. Information from this location will be erased (therefore, it is advisable to transfer all the necessary files to another medium in advance), but there will be fewer bad blocks.
If the sectors cannot be restored, move them to the backup area. Press F4 again and launch “BB: Classic REMAP” mode. Look at the SMART table after the scan is completed - the number of bad blocks should decrease.

After using the Victoria HDD, it is advisable to check the disk:

These measures will help you eliminate problems on the disk, which will ultimately lead to an increase in the operating time of the hard drive.

Using HDD Regenerator

If Victoria seems complicated, try restoring the disk and fixing the so-called bad blocks using the HDD Regenerator program. The peculiarity of this utility is that it has access to the software and hardware of the HDD. HDD Regenerator actually tries to cure bad sectors, while most programs deny access to bad blocks, as a result of which the hard drive capacity is reduced.

To fix this problem, launch Task Manager (Ctrl+Shift+Esc) and close all applications. Go to the Processes tab and end all processes running by the user. Click "Retry" to have the program try to access the disk partitions.

If the warning window appears again, restart your computer and start the system in safe mode. You can ignore the warning by clicking “Cancel” rather than “Retry”, but then HDD Regenerator will work with some restrictions.

A window resembling a command line will open. In it you will see 4 options for the program:

Checking and restoring bad blocks.
Check without recovery, display information about bad blocks.
Regeneration of bad sectors at a specific location.
Statistics output.

First select operating mode No. 2. The hard drive will be checked for bad data. The following screen will appear, asking you to specify the interval in which to search for bads. It's better to start testing from the beginning, so leave the value at "0".

After starting the disk scan, a progress bar will appear. It will be a long wait; sometimes the system will freeze - this indicates that the program has detected bad sectors and is now determining the extent of their damage.

Once the HDD surface analysis is complete, a report will appear. Study the items “bad sectors founded” and “bad sectors recovered”. These lines indicate the number of bads found and restored. If the line “bad sectors founded” contains many bad sectors, then it is unlikely that you will be able to fix the bad sectors, but you can try.

Recovering bad blocks in HDD Regenerator

Connect the USB flash drive and run the HDD Regenerator program. Select the “Boot-booting flash drive” mode. Select the connected drive and click OK. All information will be erased from the flash drive. Instead, files will be written that allow you to start DOS mode. Further:

Restart your computer.
When the system starts, start pressing the F11 key until the drive selection window appears.
Select the removable drive that contains the HDD Regenerator files.

The program will run in DOS - this mode is better suited for treating bad sectors. A window will appear that you have already seen when working in Windows. Select checking and restoring bad blocks (operation mode No. 1).
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For those who are not very familiar with a computer and do not know what DOS is, it is better not to repeat everything that will be described in this article, since here we will talk about how to restore damaged HDD sectors.

And so you discovered that you constantly have a disk check when loading, or your hard drive has started to slow down a lot. You scanned with some utility in read mode or some program from this article. Thus, you are convinced that you have slow sectors that respond longer than 500 ms, or BAD sectors, then this article is for you.

How to fix bad sectors

If your disk periodically disappears or is not visible at all, then this is most likely a problem with the controller, cable (cable) or power supply, but we will talk about BED sectors and very slowly readable cells, in general about software errors of the hard drive .

So you have discovered (HDD checking program) that you have slow sectors on your hard drive (usually red or brown). The decision to apply low-level formatting (Erase), we do it with a program MHDD and just forget about programs running under Windows, they won’t help you like HDDscan And Victoria.

Attention!!! All of the operations described below can lead to partial or complete deletion of information on your hard drive (HDD).

So, we boot from the boot disk where there is this MHDD program, these are the STEA Live, Hiren boot cd collections, or you can make a boot disk or flash drive yourself.

Stage 1. Getting rid of slow (red) sectors

Launch MHDD, type the command erase, the list of all commands can be viewed using the F1 command, the program will ask you to specify the scanning range, do not change anything, press Enter by default, wait. If there are red sectors left, you will have to run the command Erase waits

Stage 2. Getting rid of BAD sectors

We launch MHDD, type the Remap command, and the program will automatically scan the hard drive and replace bad sectors with backup ones. I do not recommend running this program if there are a large number of red and bad sectors in the hard drive partitions.

You can also clean the HDD of bad sectors manually, not the entire hard drive, but partially by address range.

Execute the command SCAN, as soon as the BAD sector appears, remember its number, stop the ESC process, run the command Erase and indicate the range in this case, if there is one bad sector, then its number and the next one, that is, we add one, then we run the command again Scan and look at the appearance of new bad sectors and repeat the procedure.

The video shows this whole process well:

If scanning takes a lot of time for you, then no program will help you. And you will have to buy a new hard drive.

P.S.: I am attaching a link to a video showing the operation of the MHDD program for general information.

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18 comments for the entry How to restore damaged bad (BAD) HDD sectors

Well, you give a hint. I booted from MHDD and wrote how you set Erase in the first point and all Windows was erased. Even restoring through the archive didn’t help. Right now I’m installing a new Windows one.

Dear yura200, if you read the article carefully, it says that Erase- this is low-level formatting, well, I hope the word formatting, do you understand what it does?)

So why write the first paragraph, write erase, it’s good that after installing Windows I was able to roll back everything right now. The most interesting thing is that I wanted to start this business with drive D and there were pictures of family videos, I would have grabbed it in grief, but it’s good that MHDD did not see drive D and only C drive was formatted. I'm pushing here so that others don't wipe out the whole screw. And where in the text do you say that Erase is formatting? When I used Mhdd I used erase when erasing bad blocks. Correct the text.

yura200, I am very sorry that you experienced such difficulties, but everything you do is your personal desire. The third paragraph in the text:

So you have discovered (HDD checking program) that you have slow sectors on your hard drive (usually red or brown). The decision to apply low-level formatting (Erase)

P.S.: And just for fun, you can look at the translation, it also says a lot erase- erase, cross out (from memory).

Good afternoon.

Can you tell me how to get the program to work on a laptop? Neither MHDD nor Victoria can see my hard drive.

Danila, Are you sure that you have an HDD in your laptop? and not an SSD, because the MHDD and Victoria programs do not work with second disks.

Dear! If you see orange or red, or even an X in a square on your disk during the test, then don’t torture it, it’s finished. They are just trying to somehow support people during a stroke, and then you see what they become later, but the glands, after you have sent photos, are the only way to a well-deserved rest. And don't listen or read nonsense about restoration.

That’s right, on the ASUS X552EA laptop the MHDD program does not see a 500 GB WD HDD (not an SSD, and not a hybrid, regular one).

I played with the BIOS - this way and that... alas, the MHDD program opens from the bootable flash drive, but does not see the disk, no matter how hard I tried.

It is necessary to set the HDD operating mode to SATA Standard IDE INSTEAD OF SATA AHCI

I want to check and fix this problem in dos (I checked it in winows with Victoria before) But I can’t switch from AHCI to IDE in the BIOS, there’s nothing similar. HP laptop (they wrote that they removed this function) How can you help?

Place this hard drive in the system unit and launch it there and, if necessary, configure the BIOS.

Respect and respect to the author! The user does not have the funds for a new hard drive, but a system engineer is vital... so I found, along the above path, that in addition to the first 42 gigs of crosses, there are two more thirds of the workspace... and the person is grateful!

Thank you very much for the article!

It was necessary to restore the functionality of the old disk. I scanned its state with the MHDD program (found on an old CD resuscitator), found several dozen “red” sectors, but did not know that the ERASE command was exactly what I needed. I thought it was a simple erasure of information.

Now, after processing the disk with ERASE, I scanned it again. The result is not a single BED!

The question is, if there are problems in the first 4 gigs and the last 4 gigs, and there are 2047 of them, is there any point in straining to recover?

Andrey, unless you need to pull the remaining data from the hard drive, but I would not use such a drive in the future.

Is 653 bads really bad? Erase won't help?

Max yeah that's really bad

Hello bortvlad. Is it worth bothering with treating bad diseases? Windows already monitors and edits cells as best it can. And he won’t write down the information in the bads. The loss of speed is negligible. And replacing cells from the backup area changes the desired table, which, in my opinion, will only accelerate the death of the HDD. If you really want low-level formatting and use the disk for archiving movies, games... What can you say about this software: Low Level Format Tool?

Bad sectors are found on almost all HDDs. Especially those that are actively used for a long time. Sometimes the problem gets out of control and turns into a real disaster, destroying all data on the HDD in any partitions. To prevent this from happening, find out how to repair bad hard drive sectors at home.

What are bad sectors and why do they appear?

You can imagine a bad block as a book with the last chapter torn out. You can read it up to a certain point. But as soon as there is a gap in the pages, you will not be able to finish reading. HDD works the same way. The magnetic head reads information within the track, but in some area it encounters a damaged surface or an empty bit of information, which makes it impossible to extract the information completely.

Almost all hard drives have broken partitions. There may be one or several, and in most cases it is not scary. But over time, there are more and more of them, and they make it increasingly difficult to operate information on the HDD. Such areas can be identified by scanning the hard drive for bad sectors using special utilities.

There can be many reasons for the appearance of bad sectors:

impact of the disc or use in improper conditions;
interrupting recording by turning off the power;
overheating and temperature surges;
natural wear and tear on the heads and writing disk;
low quality products.

Here you can divide bad sectors into non-recoverable and recoverable sectors. The first are those caused by shock or overheating. They are destroyed once and cannot be restored, and information, as a rule, disappears forever. The second type of bad sectors appears as a result of an interruption in the recording process. They can be restored by simply rewriting the disc.

Over time, write and read speeds may decrease. And after a slight fall of your laptop, the disk may stop working altogether. Everything would be really bad if it weren’t possible to somehow regenerate bad blocks. The fact is that hard drives have a certain reserve area, which means a potentially larger volume than stated on the receipt. You can use the extra space to transfer contents from damaged areas to it. How to recover bad sectors of a hard drive in this way is indicated below.

Danger is near

You can notice the problem not only after a hard drive failure, but also in the initial stages. You should be wary of the following signs:

Disk writing/reading speed has dropped;
unusual noise is heard when accessing the HDD;
began to overheat;
subjected to mechanical stress;
The system often crashes, and at startup chkdsk runs without permission.

As a rule, these reasons indicate the beginning of the end of your HDD. To avoid losing data, the first good solution would be a backup. Transfer all the necessary files to another computer, flash drive, disk, and, if possible, set up synchronization with the cloud.

Most modern hard drives check for bad sectors themselves, without user intervention. This is both good and bad, since you cannot influence the elimination of bad blocks and learn about their appearance on system partitions.

When to scan?

You can scan your hard drive for errors at a certain frequency, which depends on the frequency of use of the computer and is calculated individually. Some people carry out scheduled computer maintenance once a month, others - once every six months.

To do this, you can use system utilities or programs to restore bad sectors of the hard drive. A scan should be performed immediately after detecting the problems listed above.

Scanning using standard tools

Starting with Windows 8, the system itself is capable of scanning disks on a schedule and thereby prolonging the operation of the HDD. You can set up a scanning schedule at: “My Computer” / “Management” (a tab will appear in the main menu when the section is active). In Windows, checking your hard drive for bad sectors can be done with the standard chkdsk program. The utility can be launched in several ways:

The work is not fundamentally different, so let’s consider the first option:

Open Command Prompt as Administrator. Right-click on the Start menu icon or simply in the lower left corner on Windows 8 and select “Command Prompt (Admin)” from the list.
If you want to scan a non-system drive, enter the command with the keys chkdsk /f /r to scan and fix the entire disk at once, and chkdsk D: /f /r to fix only partition D or any other existing one. Additionally, you can enter the /x key to disable the volume being scanned during the scan. If you diagnose a working disk, the program will prompt you to reboot in order to complete the work without logging in.
If chkdsk finds errors in the partitions in use, it will offer to reboot and fix the sectors before the system starts.

To display all options, type help chkdsk. A list will appear showing all available keys with explanations. You can use any combinations at your discretion, as long as you understand the essence of what is happening and the possible consequences. At the end of the scan, all data about the operation will be displayed in the log.

Third party programs

In addition to the built-in chkdsk, you can use third-party programs to fix bad sectors on your hard drive. There are many software that can recover damaged partitions.

Among the popular free software, I would like to highlight Victoria. This program for recovering bad sectors of a hard drive is well known and at one time was very popular among repairmen. The Victoria program can work in both windowed and DOS mode, which allows it to be used even on dead systems to restore information.

Victoria interface

The program is perfect for recovering bad sectors of a hard drive. Victoria is intended more for experienced users, since it contains virtually no interface and does not even have a localization tool included. But this does not prevent it from working correctly with hardware and file systems.

There are quite a lot of settings, switches and different numbers, and when you open the program for the first time, it can be difficult to navigate. But by following the steps below, let's learn how to repair bad sectors on your hard drive.

Testing and Analysis

In the Smart tab of this program you can quickly assess the general condition of the disk. The score is assigned based on an analysis of the various values given in the table. There you can view the status of each parameter separately.

For simple testing, go to the Tests tab. There are quite a lot of settings in each section, so for the initial analysis you can leave everything at default. Click on the Start button and wait until testing is completed. A complete check of the hard drive for bad sectors takes a long time. Therefore, you can safely leave testing overnight and go to bed.

Additionally, the window contains a speed graph or a color indication of sectors. You can switch the view using the Grid checkbox next to the timer.

Correcting sectors

If you don’t have time to wait for several checks, then after assessing the condition, you can immediately begin treating bad sectors of the hard drive. Victoria uses the Remap method to rewrite blocks. It reassigns bad blocks to normal ones from the spare disk space. To repair bad sectors, do the following:

During the scan, the log will display all errors found and a report on the measures taken. It also indicates in which part of the disk the problems were detected.

How to trim?

Often, bad partitions predominate at the beginning or end of the disk. The thought immediately comes to mind: “What if we don’t use the space with bad sectors?” Yes, it can be cut off and no longer used. You can find out which partition of disk space is best to cut off like this:

You should only work with the system disk in DOS mode until the OS is loaded. While the backup or restored one can be marked directly from Windows. This method is good for large HDDs. But it does not help specifically restore broken partitions on the hard drive, as happens during the remap process.

Prevention

To prevent the hard drive from “dying” in your hands, it is advisable to carry out some preventative measures. Depending on the type of equipment.

If you have a laptop:

try not to hit him;
Do not shake too much, especially during working hours;
Do not expose to vibrations or temperature changes.

If you have a desktop computer:

do not place the system unit in a damp place;
do not allow components to overheat;
although the HDD itself is sealed, the board can be damaged by a layer of dust, so get rid of it;
Install additional cooling on the hard drive if the computer is actively used or the hard drive is unable to cool itself.

Defragmentation is a useful preventive measure for all hard drives. There are a lot of programs, both in-house and third-party, to carry it out.

Now you know how to repair bad sectors on your hard drive and maybe even be able to save valuable information on it if problems arise.

In previous articles, we have repeatedly mentioned such a phenomenon as a faulty (bad) block, but we still have not given an exact definition of what it is, what are the reasons for their occurrence, how to deal with them and whether it is necessary. In this article, we will look at the first two questions and give you some time to think and find solutions for yourself. Next time we’ll talk about methods of dealing with them.

So, by bad block we usually mean a specific section of the disk, normal operation with which is not guaranteed or is impossible at all. Such areas may contain various information, it can be user data or service information (otherwise called servo (obviously from the Latin servire or English serve - to serve), in this case this is fraught with consequences, the severity of which varies within very wide limits), although, of course, the best option would be the absence of anything in this area (though, you probably won’t have to deal with bad things in such areas). The appearance of such sectors can be due to various reasons; in one case, such sectors can be restored, in another it is impossible, in one case it is necessary to use certain methods of treatment and reassignment in another. But first, let's dispel some fairly common myths.

Myth one: there are no bad drives on modern hard drives. This is not true, it happens. By and large, the technology is the same as years ago, only improved and refined, but still not ideal (however, the ideal one is unlikely to be created on the basis of magnetic recording technologies).

Myth two: for hard drives equipped with SMART, this is not relevant (read: there cannot be bad ones). This is also not the case: it is relevant, no less than for hard drives without SMART (if there are any left). The concept of a bad sector is close and dear to her; this should have become clear from the relevant publications devoted to this technology (links at the end). The only thing is that SMART has taken on most of the worries about such sectors that were previously assigned to the user. And it can often happen that the user knows nothing at all and will not find out about the bad things that are happening on his screw, unless of course the situation is pathological. I've heard from users that this is how sellers sometimes justify their refusal to provide a warranty exchange for hard drives that have problems that have surfaced. The seller is, of course, wrong. SMART is not omnipotent, and no one has canceled the bads yet.

In order to understand bad things and their varieties, let’s delve into the method of storing information on a hard drive, just a little bit. Let's clarify two points.

1. The unit of which the hard drive operates at a low level is the sector. In the physical space on the disk corresponding to the sector, not only the data itself is recorded, but also service information - identification fields and a checksum for it, data and a control code for them, a code for error recovery, etc. (not standardized and depends on the manufacturer and models). Based on the presence of identification fields, two types of records are distinguished - with and without identifier fields. The former is old and has given up his position in favor of the latter. Later it will become clear why I celebrate this. It is also important that there are controls in place for errors (which, as we will see, can be sources of errors).

2. When working with old hard drives, it was necessary to register their physical parameters in the BIOS, which were indicated on the label, and in order to uniquely address a data block, it was necessary to indicate the cylinder number, sector number on the track, and head number. Such work with the disk was completely dependent on its physical parameters. This was not convenient, and tied the hands of the developers in many matters. A solution was needed and it was found in the address translation. The one that interests us is that it was decided to address the data in the drive with one parameter, and assign the function of determining the actual physical address corresponding to this parameter to the hard disk controller. This gave tremendous freedom and compatibility.

The actual physical data of the drive was no longer important. It is only important that the number of logical blocks specified by the BIOS does not exceed the actual number. The creation of such a translator is of great importance for the issues of bad sectors too. And that's why. Processing of bad sectors on old hard drives was not perfect and was carried out using file system tools. The disc came with a sticker that indicated the addresses of defective blocks found by the manufacturer. The user himself manually entered this data into FAT, and thus excluded the operating system from accessing it.

The technology for making plates was imperfect then, and it is imperfect now. There are no methods for creating an ideal surface that does not contain a single bad block, contrary to the popular belief that the hard drive is supplied from the factory without them. As the volume of disks grew, the number of bad sectors when leaving the factory grew, and, it is clear that only up to a certain point the procedure for registering them in FAT could be done manually; it was necessary to find a way to mark bads, even though it is not known which file system will be used. The invention of the translator made it possible to solve these problems. A special protected area was allocated on the hard drive, where a translator was written, in which the correspondence of each logical block of a continuous chain and a real physical address was established.

If a bad block was suddenly discovered on the surface, it was simply skipped, and this logical block was assigned the address of the next physical available block. The translator was read from the disk when turned on. Its creation was (and is) carried out at the factory, and it is for this reason, and not because the manufacturer uses some kind of super technology, that the new disks do not contain bad blocks. Physical parameters were hidden (and they were too varied, since firms were free to produce their own low-level formats, and the user did not care), defects were flagged at the factory, versatility increased. Good as in a fairy tale.

Now let's return to bads and their varieties. Depending on the nature of their origin, they can all be divided into two large groups: logical and physical.

Physical and logical defects

Surface defects can be associated with the gradual wear of the magnetic coating of the disks, tiny dust particles that have leaked through the filter, the kinetic energy of which, accelerated inside the drive to colossal speeds, is sufficient to damage the surface of the disks (however, most likely they will roll off the disk under the influence of centrifugal forces and will be delayed by the internal filter, but they may have time to do a mischief), the result of mechanical damage upon impact, in which small particles may be knocked out of the surface, which then, in turn, will also knock out other particles, and the process will proceed like an avalanche (such particles will also roll off the plates under the influence of centrifugal forces, but much longer and heavier, since they will be held by the forces of magnetic attraction. This is also fraught with the fact that a head floating at a very low altitude will collide with them, which will cause its heating and deterioration of performance characteristics - distortions will occur. signal, the result is reading errors), I’ve heard (I don’t have such statistics) that smoking on a computer can do the same thing, since tobacco tar can penetrate the air filter of a hard drive (which has one), causing the heads to stick there to the plates (damage to the surface and heads), simply settling on the surface, thereby changing the performance characteristics, etc.

Such sectors turn out to be unsuitable for circulation and should be excluded from circulation. Restoring them is not possible either at home or in service centers. It will be good if it is possible to at least recover information from them. The speed of the process of this type of surface destruction is individual. If the number of bads does not grow or grows very little, then there is no serious concern (although it is still worth doing backups); if the growth is rapid, then the disk will have to be replaced, and, moreover, very quickly. With this type of bad, you can reassign blocks to a backup surface: it makes sense in the absence of progression. But not about that now. This is if we talk about the data area. As already noted, service information is also stored on the plates. It may also be destroyed during use. This can be much more painful than a normal custom surface.

The fact is that servo information is actively used in the process of work: the servo marks stabilize the speed of rotation of the disks, holding the head above a given cylinder, regardless of external influences. Minor disruptions to servo information may go unnoticed. Severe damage to the servo format can render some part of the disk or the entire disk inaccessible. Since the servo information is used by the drive program and is critically important for ensuring normal functioning and, in general, due to its specificity, things are much more complicated with it. Some hard drives allow you to disable faulty servo tracks. Restoring them is only possible at the factory using special, expensive and complex equipment (let’s roughly estimate the costs of such a repair of an out-of-warranty hard drive and understand that it would be correct to call this type of bad problem incorrigible).

Physical bads can also include bad sectors, the appearance of which is caused by malfunctions of the electronic or mechanical part of the drive, for example, broken heads, serious mechanical damage as a result of an impact - jamming of the positioner coil or disks, displacement of the disks. The actions here can be different and depend on the specific situation, if, for example, the head is broken (such bad things appear because an attempt is made to access a surface that cannot be accessed (which does not mean that there is something wrong with surface)), then, for example, it can often be turned off (or it can be changed in specialized service centers, but the cost of the operation makes you seriously think about its feasibility (in most cases the answer is negative), unless, of course, we are talking about the need to restore extremely valuable information (but that's another conversation)).

In general, this type of damage is characterized by a catastrophic nature. Those. As we see, physical troubles cannot be treated, only some kind of “mitigation” of their presence is possible. With logical bad sectors the situation is simpler. Some of them are curable. Most cases are caused by recording errors. The following categories can be distinguished:

1. The simplest case: file system errors. The sector is marked in FAT as bad, but in fact it is not. Previously, this technique was used by some viruses, when on a small hard drive they needed to find a secluded place that was not accessible by simple means. Now this technique is not relevant, since hiding a couple of megabytes (or even a couple of tens of megabytes) in the depths of Windows is not difficult. In addition, someone could simply make a joke at the expense of an unlucky user (there were such programs). And in general, the file system is a fragile thing, it can be treated very easily and with absolutely no consequences.

2. Uncorrectable logical problems - typical for old hard drives that use records with identifier fields. If you have such a disk, then you may well encounter them. Caused by an incorrect format of the physical address recorded for this sector, a checksum error for it, etc. Accordingly, it is impossible to contact him. In fact, they are rebuildable, but at the factory. Since I have already said that recording technology without identifier fields is now used, this type can be considered irrelevant.

3. Correctable logical problems. A type of bad blocks that is not so rare, especially on some types of drives. The origin is mainly due to disk write errors. It is not possible to read from such a sector, since usually the ECC code in it does not correspond to the data, and writing is usually impossible, since before writing, a preliminary check of the space to be written is carried out, and since problems have already been detected with it, writing to this area is rejected. Those. It turns out that the block cannot be used, although physically the surface it occupies is in perfect order. Defects of this kind can sometimes be caused by errors in the hard drive firmware, or can be triggered by software or technical reasons (for example, a power failure and fluctuations, the head moving to an unacceptable height during recording, etc.). But if it is possible to match the contents of the sector and its ECC code, then such blocks pass without a trace. Moreover, this procedure is not complicated, and the means for its implementation are widely available and, in general, harmless.

4. The appearance of bad blocks of this type on hard drives is due to the peculiarities of production technology: there are never two absolutely identical devices, some of their parameters will certainly differ. When preparing hard drives at the factory, for each one a set of parameters is determined that ensures the best functioning of this particular instance, the so-called adaptives. These parameters are saved, and if they are somehow mysteriously damaged, the result may be complete disk inoperability, unstable operation, or a large number of bad sectors appearing and disappearing in one place or another. There is nothing you can do about this at home, but everything can be set up at the factory or at a service center.

As you can see, only two types of logical bad blocks can actually be treated at home. Others, if necessary, can be replaced with backup ones, but cannot be cured. Nothing can be done about the third houses. We will talk about how and what needs to be done in the first two cases next time.

To be continued