Computer hard drive traces eliminate

1, the system does not recognize the hard drive

This type of failure is more common, that is, from the hard disk can not start, starting from a disk can not enter the C disk, the use of the CMOS automatic monitoring function can not find the existence of the hard disk. Most of this fault occurs in the connection cable or IDE port, the hard disk itself failure rate is very small, can be replaced by reseating the hard drive cable or change the IDE port and cable, etc. to replace the test, you can quickly find fault. If the new hard drive is not recognized, there is a common reason for the main line on the hard disk, if the hard disk is connected to the IDE's master disk position, the hard disk must skip the main disk, and jumper errors generally cannot detect the hard drive.

2, CMOS caused by the fault

Whether the CMOS is correct or not directly affects the normal use of the hard disk, mainly refers to the type of hard disk. Fortunately, today's machines support the "IDE Auto Detect" function, you can automatically detect the type of hard disk. This feature is used to reset the type after a new hard drive is connected or a new hard drive is replaced. Of course, there are now types of motherboards that can automatically identify the type of hard disk. When the hard disk type is wrong, sometimes it is impossible to start the system, sometimes it can start, but read and write errors occur. For example, the hard disk type in CMOS is less than the actual hard disk capacity, then the sectors behind the hard disk will be unable to read and write, and the individual partitions will be lost if they are multiple partition states. There is also an important cause of failure, because the current IDE supports the logical parameter types, the hard disk can be normal, LBA, large, and so on. If you install the data in a normal mode, and then change to another mode in the CMOS, you will have a hard drive reading and writing error, because its physical geology mapping relationship has changed, will not be able to read the original correct hard disk location.

3. Boot failure caused by the main boot program

The main boot sector of the hard disk is one of the most sensitive parts of the hard disk, and the main boot program is part of it, which is used primarily to detect the correctness of hard disk partitions and to determine the active partition, which is responsible for handing over the boot to the DOS or other operating system of the active partition. This piece of program corruption will not boot from the hard drive, but can read and write to the hard drive from the soft zone or the light area. The easiest way to fix this failure is to use a high version of DOS for FDISK, which will replace (override) the hard drive's main boot program directly when you run with the parameter/mbr. Actually, the main boot sector of the hard disk is the program that was created, Fdisk. EXE contains the complete hard drive master boot program. Although the DOS version is constantly updated, the hard drive's master boot program has not changed from DOS 3. X to currently have WinDOS 95 dos, so just find a DOS boot disk to boot the system and run this program can be repaired. In addition, other tool software, such as kv300, also has this feature.

4, partition table error-guided boot failure

The partition table error is a serious error on the hard drive, and the degree of error can cause different losses. If there is no active partition flag, the computer will not start. However, you can read and write to the hard disk after booting the system from a soft zone or a light area, and you can repair it by using the Fdisk reset active partition. If it is a partition type error, it can cause a partition to be lost. The fourth byte of the partition table is the partition type value, and the normal bootable 32MB primary DOS partition value is 06, while the Extended DOS partition value is 05. If you change the basic DOS partition type to 05, you cannot start the system, and you cannot read and write data from it. If you change the 06 to DOS unrecognized type such as EFH, DOS thinks the partition is not DOS partition, of course, can not read and write. Many people use this type of value to implement a single partition of encryption technology, restore the original correct type value can make the partition back to normal. There are other data in the partition table to record the starting or ending address of the partition. The corruption of these data will cause confusion or loss of the partition, it is generally not possible to manually recover, the only way is to use the Backup partition table data to write back, or from the other same type and partition status of the same hard drive to get the partition table data, otherwise will cause other data permanent loss. In the operation of the main boot sector, NU and other tools can be used, the operation is very convenient, can directly to the hard disk main boot sector to read or write or edit. Of course, you can also use debug to operate, but the operation is cumbersome and has a certain risk.

5, the partition valid mark error caused by the hard disk failure

An important part of the hard drive's main boot sector is the last two bytes: 55aah, which is a valid flag for the sector. When booting from a hard disk, floppy disk, or light area, the two bytes will be detected and the hard drive will not be recognized if it exists. This flag when booting from the hard drive will be transferred to ROM Basic or prompted to put the floppy disk. cannot be transferred to the hard drive when booting from a floppy disk. This can be used for encryption of the entire hard drive. You can use the Debug method for recovery processing. In addition, the DOS boot sector still has such a flag, and when the DOS boot sector does not have a boot flag, the system boot will appear as: "Missing operating system". The method of repair can be used in the main boot sector repair method, but the address is different, more convenient method is to use the following DOS system common repair method.

6. Boot failure caused by DOS boot system

The DOS boot system consists of DOS boot sector and DOS system files. System files mainly include Iosys, Msdos.sys, Command.com, where Command.com is a DOS shell file, can be replaced with other similar files, but the default state is a DOS boot prerequisite files. In the DOS system that Windows 95 carries, Msdos.sys is a text file, which is the necessary file to start Windows. However, you can use this file only when starting DOS. However, when a DOS boot error occurs, boot the system from a floppy disk or CD, and then use the SYS C: delivery system to fix the failure, including the boot sector and the system files automatically repaired to the normal state.

7, Fat table caused by read and write failure

The Fat table records the storage address of the hard disk data, and each file has a set of connected fat chains that specifies the cluster address to which it resides. The corruption of the fat table means the loss of the contents of the file. Fortunately, the DOS system itself provides two fat tables, and if the fat table currently in use is damaged, the second one can overwrite the repair. However, because the size of different sizes of the disk its fat table and the address of the second fat table is also not fixed, so repair must correctly find its correct location, by some tool software such as Nu and so on itself with such a repair function, the use is very convenient. With debug, you can do this by moving the second fat table to the first table with its M command. If the second Fat table is also corrupted, the hard drive cannot be restored to its original state, but the file's data is still stored in the data area of the hard disk, and can be repaired using CHKDSK or ScanDisk commands, which will eventually be *. CHK file, this is the loss of the fat chain sector data. If it is a text file, you can extract and merge the complete file, and if it is a binary data file, it is difficult to recover the complete file.

8, Directory table damage caused by the boot failure

The catalog table records data such as the file name of the files on the hard disk, the most important of which is the starting cluster number of the file, and the directory table has no automatic backup function, so a large number of files will be lost if the directory is corrupted. A method of reducing loss is also the use of the above Chkdsk or ScanDisk program method, from the hard disk to search out the Chk file, by the table damage is the first cluster number is lost, in the case of fat damage to the formation of the CHK documents are generally relatively complete file data, Each chk file is a complete file, change it to the original name to restore most of the files

9, mistakenly delete the partition when the data recovery

When you remove a hard disk partition with Fdisk, the surface phenomenon is that the data on the hard disk has completely disappeared, and when it is not formatted, the drive will appear invalid. If you understand how FDISK works, you'll know that Fdisk simply rewrites the contents of the hard drive's main boot sector (0-side 0-1-sector). Specifically, delete the hard disk partition table information, and the hard disk of any partition of the data has not changed, you can imitate the above partition Table error repair method, that is, to find a way to restore the partition table data can restore the original partition that data, but this is limited to partition or rebuild after partition. If the partition is formatted with format, after the partition is restored, the partition data is restored in the following way.

10, incorrectly formatted hard disk data recovery

In the DOS High version state, the format operation format establishes the disk information that is used to recover the formatted disks by default, and in effect copies all the contents of the disk's DOS boot sector, the FAT partition table and the table of contents to the last few sectors of the disk (because the following sectors are rarely used), and the content in the data area has not changed at all. This way by running "Unformat C:" Can restore the original file allocation table and table of contents, so as to complete the recovery of hard disk information. In addition, DOS also provides a miror command to record the current disk information for reuse after formatting or deletion, and this method is also more effective.