[Operation and Maintenance Engineer Learning] Disk
1、DOS（Disk Operating System）
DOS is Disk Operating Systeman abbreviation in English, meaning " disk operating system ". As the name suggests, DOS is mainly a disk-oriented system software. To put it simply, DOS is a bridge between man and machine, and it is a "shell" covering the machine hardware. machine instructions. Most of the daily operations can be easily completed through some DOS commands close to natural language. In addition, DOS can effectively manage various software and hardware resources and schedule them reasonably. All software and hardware are under the monitoring and management of DOS, and they are doing their work in an orderly manner. The next will crash.
The family includes 86-DOS、MS-DOS、PC-DOS、DR-DOS、FreeDOS、PTS-DOS、ROM-DOS、JM-OS等, among which MS-DOS is the most famous. Although these systems are often referred to simply as "DOS", few systems are named after "DOS" alone (except for an unrelated 1960s IBM mainframe operating system named after it). In addition, several non-DOS-related disk operating systems that run on non-x86 microcomputer systems also have "DOS" in their names, and are also shortened to "DOS" when discussing the machine specifically (for example: AmigaDOS, AMSDOS, ANDOS, AppleDOS, Atari DOS, Commodore DOS, CSI-DOS, ProDOS, TRS-DOS, etc.), but these systems are not compatible with DOS executables and MS-DOS API.
2. Hard disk bad sectors
(1) Logical bad sectors
In general, bad sectors can be divided into physical bad sectors and logical bad sectors. Among them, logical bad sectors are relatively easy to solve. It means that the hard disk is accidentally disturbed when writing, causing damage ECC错误. In terms of process, it means that when the hard disk writes data, it will use ECC logic to recombine the data. Generally , the operating system needs to write 512个字节, but in fact the hard disk will 多写几十个字节, and all these bytes must be corrected with ECC. If the ECC correction code calculated by the original byte is different from the ECC calculated by the read byte, an ECC error will occur, which is the cause of the so-called logical bad track.
(2) Physical bad sectors
As for the physical bad track, it is more fatal to the damage to the hard disk . It also has the difference between soft and hard physical bad track. The physical damage to the disk surface is hard, which cannot be repaired. When the data is written incorrectly due to external influences, the system will also consider it as a physical bad track, and this kind of physical bad track can be repaired with some hard disk tools (such as detection and repair software provided by the hard disk manufacturer) . In addition, for For minor hard disk surface damage, some hard disk tools (such as Western Digital's Data Lifeguard Tools) can redirect to a good reserved sector to correct the error.
For these types of bad sectors, hard physical bad sectors are definitely irreparable, it is the most direct damage to the surface of the hard disk, so it cannot be repaired even if you lower the format or use hard disk tools (unless it is a very small damage, Some tools can keep this part of the bad track and do not use it to solve the problem).
(3) Check for bad sectors
①When opening and running files, the speed of the hard disk is obviously slowed down; or the hard disk "click" sound is obviously heard, and sometimes Windows will prompt that the file cannot be read or written.
②Automatically scan the disk every time it is turned on, which indicates that the hard disk has errors that need to be repaired. If the program does not pass, it means that the hard disk has bad sectors; or the scan passes, but is marked with a red "B" in some places.
③The hard disk cannot be booted. After booting with a floppy disk or CD, the drive letter of the hard disk can be seen, but it cannot be operated; or the drive letter cannot be seen at all. ④ When reading a certain file or running a certain program, the hard disk repeatedly reads the disk and makes an error, prompting information such as file corruption, or it takes a long time to succeed; sometimes even a blue screen appears.
⑤ The sound of the hard disk suddenly changed from a normal friction sound to a strange sound.
⑥If the virus infection is ruled out, the system cannot start normally, and prompt information such as " Sector not found" or " " appears. ⑦When formatting the hard disk, it stops at a certain progress, and finally reports an error and cannot complete it. ⑧Every time the system is turned on, it will automatically run Scandisk to scan for disk errors. ⑨When formatting the hard disk, it will advance and retreat repeatedly at a certain progress. ⑩The system cannot be booted through the hard disk at startup.General error in reading drive C
(4) Reason
There are many reasons for hard disk bad sectors, including its own quality problems, improper hard disk maintenance, and user reasons, such as sudden power failure during use. In addition to the quality of the hard disk itself and aging reasons, the bad sectors of the hard disk are mainly due to the fact that the hard disk cannot be treated well in daily use, such as too little memory so that application software frequently accesses the hard disk, defragments the hard disk too frequently, improper overclocking, Poor quality, high temperature, poor dustproof, vibration, etc.
(5) Repair
Repair logical bad sectors
Start with the easiest method first. With the help of the disk scanning tool under Windows, right-click the drive letter in the explorer, select "Tools→Start Check" in the pop-up drive properties window, set the scan type to full scan, and select automatic Fix errors, then click Start, scan time will vary depending on disk capacity and scan options.
If the logical bad sectors exist in the system area and cannot start normally, we can use the Windows PE boot disk, type: Scandisk drive letter at the DOS prompt, press Enter, once bad sectors are found, the program will prompt you whether to Fix it (Repair), select Yes to start repairing. Many problems that cannot start Windows normally due to logical bad sectors in the system area can generally be solved by this method.
Because Windows PE only automatically repairs logical bad sectors to a large extent, but cannot automatically repair physical bad sectors, so, in fact, the first method often does not work. What should we do if we encounter physical bad sectors?
Check with Scandisk
Scandisk can't do anything about physical bad sectors. It can only mark them as bad sectors and no longer read and write to this area. Physical bad sectors are "contagious" and spread to the surrounding area, resulting in data stored near the bad sectors. are also at risk.
When using Scandisk, stop when bad sectors are found. Pay attention to observe the value when Scandisk stops, such as 22%. Assuming that the total capacity of the hard disk is 2GB, the starting position 2GB×22%=0.44GBof bad sectors on the hard disk is roughly 440MB. Because the hard disk is prone to bad sectors Peripheral diffusion, so you must leave enough buffer space, set the capacity of the first partition of the hard disk to 400MB, and divide the remaining 1.6GB into 8 partitions in units of 200MB, use Scandisk to check all partitions, and delete partitions that cannot pass Scandisk detection or hidden to ensure that the system no longer reads or writes to these areas. The remaining adjacent partitions can be merged and used. Operations such as partitioning, hiding, deleting, merging, etc. can be performed using tools and software such as PartitionMagic or DiskMan with a graphical interface.
Use software to hide physical bad sectors
Use PartitionMagic5.0/6.0to process the hard disk. PartitionMagic can repartition the hard disk, dynamically change the size of the partition, change the file format of the partition, hide or display the existing partition, etc. without destroying the data. Copy the DOS version of PartitionMagic5.0/6.0 to a floppy disk, use the Windows PE boot disk to guide the system, and run PQMAGIC.EXE on the floppy disk.
Then scan the hard disk, you can directly use the "check" command under the Operations menu in PartitionMagic. After marking the bad cluster, you can try to retest it by selecting "Advanced/badSector Retest" under the Operations menu; After dividing the bad cluster into one (or several) areas, hide the partitions containing bad sectors through the HidePartition menu item, so as to avoid misoperation in Windows.
Special reminder: If the partition with bad sectors is hidden directly without formatting, then some programs related to the drive letter will not be able to run correctly in the subsequent partitions of the partition due to the change of the drive letter. The solution is to use the DriveMapper menu item under the Tools menu, which will automatically collect shortcuts and relevant information in the registry, and immediately update the drive letter parameters in the application to ensure the normal operation of the program.
Repair hard disk sector 0 bad sector
For the case of hard disk sector 0 damage, although it is tricky, it is not hopeless. Here we introduce two methods for you.
The first method: we borrow the DiskMan software to repair. The specific method is as follows:
① Run DiskMan in pure DOS mode, select the drive symbol in the "hard disk" menu, and the main interface shows that the partition format of the hard disk is FAT32, the starting cylinder is 0, the starting head is 1, and the total capacity 2GB;
② Then enter "Tools→Parameter Modification" (or press F11) in turn, and in the pop-up Modify Partition dialog box, change the value of the initial cylinder from "0" to "1"
③Press OK to return to the DM main interface and press F8 to save the modification result. The hard drive needs to be reformatted after modification.
The second method: we use the DE tool in the Pctools9.0 software that some people are familiar with. The specific method is as follows:
① Start with the Windows PE boot disk, run DE.EXE under the Pctools9.0 directory, first enter the Options menu, select Configuration (configuration), press the space to remove the hook in front of Read Only (press the Tab key Switch), save and exit
②Then select Drive in the main menu Select;
③After entering, select Physical in the Drive type item, press the space to select, and then press the Tall key to switch to Drives item, select Hard disk (hard disk), and then select OK to enter;
④ After that, return to the main menu, open the Select menu, and then Partition Table (partition table) will appear, select and enter, and then the hard disk partition table information will appear
⑤If The hard disk has two partitions, and the l partition is the C drive. This partition starts from the 0 cylinder of the hard disk. Then, change the 0 of the Beginning Cylinder (starting cylinder) of the 1 partition to 1. ⑥Save and
exit ;
⑦ Restart, press the Delete key to enter the COMS settings, select "IDE AUTO DETECT", you can see that CYLS is reduced by 1, save and exit, repartition, format, and you're done.
Tips: Before modifying, back up the important data on the hard disk first, and Pctools9.0 cannot run on the hard disk partitioned by FAT32 or under Windows, but it can run on the FAT16 hard disk. After repairing, be sure to re-detect the hard disk in CMOS, then partition and format, because the information of the partition table will be written into sector 1 (it has been changed to sector 0) only after the hard disk is formatted.
Low-level formatting to repair bad sectors
If none of the above methods are effective, and you are not willing to scrap the hard disk, you can consider using low-level formatting to deal with the hard disk failure. However, low-level formatting will re-divide tracks and sectors, label address information, set crossover factors, etc., which requires a long time to read and write the hard disk, and will cause severe wear and tear to the hard disk every time it is used. To add insult to injury, practice has proved that low-formatting will accelerate the scrapping of hard disks with physical bad sectors, and for logical bad sectors, there is no need to use low-format programs as a repair method. In addition, the low format will completely erase all data in the hard disk, and this process is irreversible. Therefore, the low-level format can only be used as a last resort, and the low-level hard disk can only be used after advanced formatting using the Format command.
3. Cylinder
The most basic component of a hard disk is a disk made of hard metal material coated with a magnetic medium, and the number of disks in a hard disk with different capacities varies.
- Each platter has two sides on which information can be recorded.
- The disk is divided into many fan-shaped areas, each area is called a sector, and each sector can store
128×2的N次方（N=0，1，2，3）byte information . - In DOS, each sector is
128×2^2=512a byte . On the surface of the disk, the center of the disk is the center, and the concentric circles with different radii are called tracks. - A hard disk is usually composed of a group of overlapping platters, and each platter is divided into equal number of tracks, numbered from the " " on the outer edge, and the
0tracks with the same number form a cylinder, (that is, a cylinder is a three-dimensional concept , the track is a plane concept, on the same disk, the cylinder size is the sum of the track sizes of all the disks with the same radius), which is called the cylinder of the disk. - The number of cylinders of a disk is equal to the number of tracks on a disk, but the capacity of each cylinder is = track capacity * number of disks.
- Since each disk surface has its own magnetic head, the number of disk surfaces is equal to the total number of magnetic heads. The so-called CHS of the hard disk, that is, Cylinder (cylinder), Head (head), Sector (sector) , as long as the number of CHS of the hard disk is known, the capacity of the hard disk can be determined. The capacity of the hard disk = the number of cylinders, the number of heads, and the number of single tracks . The number of sectors * the sector size of a single capacity (generally the initial value is 512 bytes).
Note that the initial sector size of some special hard disks is not 512 bytes, and you can also customize the sector size when partitioning. It is recommended that 4K is the optimal solution.
4. Sector
A sector refers to an area divided on a disk. Each track on the disk is equally divided into several arcs, and these arcs are the sectors of the disk, and the basic unit for reading and writing of the hard disk is the sector.
- Each side of a disk is divided into tracks, concentric circles on the surface that get smaller as you get closer to the center. And each track is divided into equal parts by 512 bytes, which are called sectors. In the parameter list of some hard disks, you can see the parameters describing the number of sectors of each track. It is usually identified by a range. For example, 373~746, which means that the outermost track has 746 sectors, and the innermost track has 373 sectors, so it can be calculated that the capacity of the tracks is from 186.5KB to 373KB (190976B–381952B) .
- When a disk drive reads and writes data to a disk, it uses sectors as the unit. On the disk, the DOS operating system
簇allocates disk space for files in units of " ". The cluster of a hard disk is usually multiple sectors, which is related to the type of disk, DOS
version and the size of the hard disk partition. Each cluster can only be occupied by one file. Even if the file is only a few bytes, it is absolutely not allowed for more than two files to share a cluster, otherwise it will cause data confusion. This mechanism, which uses clusters as the smallest allocation unit, makes it relatively easy to manage data on the hard disk, but it also causes,磁盘空间的浪费especially in the case of a large number of small files, a large gigabyte hard disk to waste disk space. The space can reach hundreds of megabytes. - In order to search and manage the sectors, the sectors need to be numbered. The numbering of the sectors starts from track 0, the starting sector is sector 1, followed by sector 2, sector 3..., track 0 After the sector numbering ends, the starting sector of track 1 is numbered cumulatively until the last sector of the last track (n sector). For example, a hard disk has 1024 tracks, each track is divided into 63 sectors, then the sector number of track 0 is 1~63, the start sector number of track 1 is 64, the last sector number of the last track is 64512 .
- The hard disk has some differences from the floppy disk in the sector numbering. In one track of the floppy disk, the sector numbers are arranged once, that is, 1, 2, 3... n sectors. Due to the high speed of the hard disk, after the magnetic head completes the reading and writing of a certain sector of data, it must transmit the data to the microcomputer, which takes a while, but at this time the hard disk continues to rotate at a high speed. By the second sector, the disk has rotated to another sector. Therefore, in the early hard disks, the sector numbers were arranged by jumping according to a certain interval coefficient.
5. Track
Tracks on a magnetic disk are a set of concentric circles with different recording densities. Magnetic surface memory is coated with a magnetic material layer on carriers of different shapes (such as disks, tapes, etc.). On the magnetic layer, the tracks of this information are called tracks. The magnetic tracks of the magnetic disk are concentric circles, as shown in the figure on the right. The magnetic tracks of the magnetic tape are straight lines along the length of the magnetic tape. These magnetic tracks cannot be seen with the naked eye at all, because they are only some magnetized areas on the disk surface that are magnetized in a special way. , the information on the disk is stored along such a track. Adjacent tracks are not next to each other, because the magnetization will affect each other when the magnetization units are too close together, and it will also make it difficult for the head to read and write. An old-fashioned 1.44MB 3.5-inch floppy disk has 80 tracks on one side, while the track density on a hard disk is far greater than this value, usually tens of thousands of tracks on one side.
6. Data area
The data area is the area actually used to store user data. In FAT32the file system, the data area follows the second FAT table and is divided into clusters. So the clusters are numbered sequentially starting from 2, that is to say, in the FAT32 file system, 2号簇的起始位置就是数据区域的起始位置.
(1) Contents of the data area
The content of the FAT32 file system data area is mainly composed of three parts: 根目录、子目录和文件内容. In the data area, this space is managed in units of "clusters", and the number of the first cluster is "2".
(2) Analysis of the root directory of the data area
The root directory has been created when the file system is established, and its purpose is to store directory entries of subdirectories or files . When the file system is created, no data is stored yet, and there is no content under the root directory. The file system only allocates a cluster (usually cluster 2) space for the root directory, and writes the end mark to the cluster The corresponding FAT entry indicates that the cluster has been allocated and used. At this time, there is no content in the space allocated by the root directory. If a volume label is specified for the disk when creating the file system, a volume label directory entry will be created for it in the root directory, and the directory entry occupies the root directory. The location of the first directory entry in . When creating a new directory or file under the root directory, it is actually creating a directory entry for it in the cluster allocated for the root directory, and if necessary, allocate space for it in the unallocated space to store data content.
(3) Analysis of subdirectories in the data area
We refer to all directories other than the root directory as subdirectories, whether subdirectories of the root directory or subdirectories of subdirectories of the root directory. In the FAT32 file system, except the space created and allocated for the root directory when the file system is created, all other subdirectories are created as needed during use. When creating a new subdirectory, create a directory entry for it in its parent directory, allocate a cluster to it in free space and perform a zero-clearing operation on the cluster, and record the cluster number in its directory entry. When creating a subdirectory, a directory entry is established in the cluster assigned to its parent directory, and the directory entry describes the starting cluster number of this directory. While creating directory entries for subdirectories, the first two directory entries are used to describe its relationship to the parent directory in the cluster allocated for the subdirectory. One of them is the "." directory item, which describes some information of the subdirectory itself; the other is the "..." directory item, which describes the relevant information of the parent directory of the subdirectory. In this way, a link is established between a subdirectory and its parent directory.
(4) Data area directory item
In the FAT32 file system, directory entries can be divided into four types according to different structures: volume label directory entry, "." directory entry and "..." directory entry, short file name directory entry and long file name directory entry. The short file name directory entry is the most important data structure, which stores information such as the short file name, attributes, starting cluster number, time value, and content size of the subdirectory or file.
7. ECC memory
- ECC memory, that is, a memory module that implements error checking and correction technology (ECC). Generally, it is mostly used on servers and graphics workstations, which will make the entire computer system more secure and stable during work. ECC is the abbreviation of "Error Checking and Correcting", and the Chinese name is "Error Checking and Correcting".
- In the memory, ECC can tolerate and correct errors, so that the system can continue to operate normally without being interrupted by errors, and ECC has the ability of automatic correction, which can detect the error bits that cannot be detected by Parity and correct the errors. fix.
- Most of the entry-level low-end servers launched by some manufacturers use SDRAM for ordinary PCs without ECC function, so you should pay attention to this indicator when purchasing.
(1) Technical principle
To understand ECC technology, you have to mention Parity (parity check). Before the emergence of ECC technology, the most widely used technology in memory is Parity (parity). We know that in digital circuits, the smallest unit of data is called "bit (bit)", also called data "bit", "bit" is also the smallest unit in memory, it is represented by "1" and "0" Data high and low level signals. In a digital circuit, 8 consecutive bits are a byte (byte). Each byte in a memory without "parity check" has only 8 bits. If an error is stored in one of its bits, it will cause The corresponding data stored in it changes and causes an error in the application. The memory with "parity check" adds an extra bit to each byte (8 bits) for error detection. For example, a certain value (1, 0, 1, 0, 1, 0, 1, 1) is stored in a byte, and each bit is added together (1+0+1+0+1+0+1 +1=5). If the result is odd, the parity bit is defined as 1 for even parity, and 0 otherwise; for odd parity, the opposite is true. When the CPU returns to read the stored data, it will add the data stored in the first 8 bits again, and calculate whether the result is consistent with the check digit. When the CPU finds that the two are different, it will try to correct these errors, but Parity has a shortcoming. When the memory finds an error in a certain data bit, it may not be able to determine which bit, and it may not be able to correct the error. , so the main function of memory with parity is only to "find errors", and it cannot correct some simple errors.
Through the above analysis, we know that the Parity memory checks the correctness of the current 8-bit data by adding a data bit on the basis of the original data bit, but with the increase of the data bit, the data bits used by Parity to check also increase exponentially. That is to say, when the data bit is 16 bits, it needs to add 2 bits for checking, when the data bit is 32 bits, it needs to add 4 bits, and so on. Especially when the amount of data is very large, the probability of data errors is greater, and the method of parity checking, which can only correct simple errors, seems powerless. It is based on such a situation that a new memory technology is allowed. It happened, this is ECC (Error Checking and Correction), this technology is also implemented by adding a parity bit to the original data bit. The difference is that the methods of increasing the two are different, which leads to the difference in the main functions of the two. It differs from Parity in that if the data bits are 8 bits, 5 bits need to be added for ECC error checking and correction. Every time the data bits double, ECC only adds one check bit, that is to say, when the data bits are 16 bits The ECC bit is 6 bits, the ECC bit is 7 bits when the data bit is 64 bits, and the ECC bit is 8 bits when the data bit is 64 bits, and so on. Every time the data bit doubles, the ECC bit only increases by one.
(2) Errors in ECC memory
When it comes to server memory, everyone unanimously emphasizes the need to buy ECC memory. They think that ECC memory is fast, but this is actually a misunderstanding. memory type), but because it has special error correction capabilities that keep the server stable . ECC itself is not a type of memory, nor is it a memory-specific technology. It is a kind of instruction error correction technology widely used in computer instructions in various fields. Its full English name is " Error Checking and Correcting", and the corresponding Chinese name is "error checking and correction". From this name, we can see that its main function is "finding and correcting errors", which is more advanced than parity correction technology. The main reason is that it can not only find errors, but also correct these errors. After these errors are corrected, the computer can correctly perform the following tasks to ensure the normal operation of the server. The reason why it is not a memory model is because it is not a technology that affects memory structure and storage speed, it can be applied to different memory types, just like the "parity correction" we mentioned earlier Memory, it is not a kind of memory, EDO memory is the first application of this technology, SD memory is also used, and ECC memory is widely used mainly from SD memory, and the new DDR, RDRAM also have corresponding applications, the mainstream ECC memory is actually a kind of SD memory.
As of August 9, 2020, the memory with ECC verification needs to be supported by other computer components before it can be used normally, such as the motherboard and cpu (and may need to be set in the BIOS accordingly). It is used in most server cpu and on the motherboard (some non-server CPUs and motherboards also support it). Also, when purchasing ecc memory, you should pay attention to whether it is ecc udimm, ecc rdimm, ecc lrdimm, ecc 3ds rdimm or others. Your configuration may not support some types.
8. Low-level formatting
Low-level formatting is to re-clear the contents of the disk, restore the factory state, divide the cylinders and tracks, and then divide the tracks into several sectors, and each sector is divided into identification part ID, interval area GAP and data Area DATA etc. Low-level formatting is a job before high-level formatting. It can be done not only in DOS environment, but also in Windows NT system. Low-level format can only be used for a hard disk and cannot support a single partition. Each hard disk has been low-level formatted by the hard disk manufacturer before leaving the factory, so users generally do not need to perform low-level formatting.
(1) Low grid effect
1. Hard disk bad track and low format
For logical bad track or soft physical bad track on the hard disk, the logical bad track will be automatically repaired when it is low format, and the soft physical bad track will be shielded, that is, it will be hidden. The low-level HDD can delete all partitions in the original hard disk, but the bad sectors still exist. Shielding just hides the bad sectors and prevents users from using these bad sectors when storing data. This can guarantee the security of user data to a certain extent. Reliability, but bad sectors will spread with the increase of hard disk partitions and formatting times. Therefore, it is not recommended for users to perform low-level formatting on the hard disk. If the hard disk is within the warranty period, it is best to go to the warranty or find a dealer to replace it. This can be said to be the best solution and the most thorough solution. If the hard disk is not allowed to be replaced after the warranty period, you can try low-level formatting of the hard disk to prevent data loss caused by storing data in bad sectors.
2. Computer viruses and low-level formatting of the hard disk
When a large number of viruses invade a certain sector of the computer hard disk, it is difficult to delete it by general formatting. The main reason for this phenomenon is that the computer cannot enter the normal working interface. No matter how you use the system disk to format and install the computer, it still cannot work normally after the system is installed. Some virus file systems use the encoding method of prefix and suffix encryption. General formatting is difficult to remove viruses, that is to say, after the encryption of the prefix and suffix codes of virus files, general formatting of the occupied disk sectors can be prevented. For this point, ordinary computer users are not clear, they always think that something is wrong with the computer, and they don't know what storage area of the computer the virus has invaded.
If the computer finds the above problems, we can only perform low-level formatting on the hard disk. The so-called computer low-level formatting is to perform high-intensity magnetization on the magnetic recording track (track) of the hard disk sector, and eliminate the virus files stored in the disk sector. After the low-level format, perform conventional format partition and load the software operating system, the computer can resume normal operation. The low-level format of the hard disk generally uses the lformat low-level format command in the dos command of the system installed disk, also known as the computer dos system format. The following introduces one of the most popular computer virus removal methods, which can basically remove all computer viruses, and is also an antivirus method when the computer is in safe mode. When the computer is working in safe mode, the virus files of the computer are generally in a non-running state. Because it is difficult for us to completely remove the virus files of the computer when they are in the running and copying state, so to kill stubborn computer viruses, the virus must be in a non-working state before it can be removed with anti-virus software. When the computer is turned on, we press the F8 key above the keyboard to make the computer enter the operation option step, use the up and down keys to select safe mode operation and then press the Enter key, and the computer system automatically enters the safe mode working mode. At this time, we can use the anti-virus software that has been downloaded to carry out anti-virus. After the anti-virus is completed, the computer will automatically restart and return to work in the normal state mode. We use anti-virus software to clean the computer from viruses. If the stubborn virus of the computer cannot be removed by the above methods, then the only option is to perform a low-level format on the hard disk. 166.238
9. Advanced formatting
Advanced formatting, also known as logical formatting, refers to writing specific data in a specific area of the disk according to the file system selected by the user (such as FAT12, FAT16, FAT32, NTFS, EXT2, EXT3, etc.) , so as to initialize the disk. or disk partition, an operation that clears all files in the original disk or disk partition. Advanced formatting includes rewriting the corresponding area of the partition table in the master boot record, and according to the file system selected by the user, a disk space for storing file allocation tables, directory tables, etc. for file management is allocated in the partition, so that Users use this partition to manage files.