Notebook Common trouble and solution summary

In order to effectively save the data in the hard disk, in addition to regular backup work, but also learn how to save the hard disk in the failure of the drive, or from the bad area to extract useful data, to minimize the loss.

First, the system does not recognize the hard drive

The system can not boot from the hard drive, boot from a disk can not enter the C disk, the use of the CMOS automatic monitoring function can not find the hard drive. Most of this fault occurs on the connection cable or IDE port, the hard disk itself failure is not possible, by reseating the hard drive cable or change the IDE port and cable, etc. to replace the test, you will quickly find fault. If the newly connected hard drive is not accepted, a common reason is the master and slave jumper on the hard disk, if an IDE hard drive cable is connected to two hard disk devices, it is necessary to know the master-slave relationship.

Note: For notebook situation, boot press F2, into the BIOS, see primary hard driver is not able to identify hard disk capacity.

　Two, the fault caused by CMOS

The correct type of hard disk in CMOS directly affects the normal use of hard disk. Today's machines support the "IDE Auto Detect" feature, which automatically detects 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 type, the hard disk can be "Normal,lba,large" and so on, if the general mode of installation of data, and in the CMOS to other modes, then the hard disk read and write error, Because its mapping relationship has changed, it will not be able to read the original correct hard drive location.

Third, boot failure caused by the main boot program

The main boot program is located in the main boot sector of the hard disk and is used primarily to detect the correctness of the hard disk partition 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 disk after booting from the floppy or optical drive. 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, but the hard drive's main boot program has not changed from DOS 3.x to WinDOS 95 dos, just find a DOS boot disk boot system and run this program to repair.

Iv. boot failures caused by partitioned table errors

Partitioned table errors are a serious error on the hard drive, and different error levels 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 the floppy or optical drive, 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. 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. Corruption of this data can result in confusion or loss of the partition, either by using the Backed-up partition table data to be written back, or by obtaining the partitioned table data from other hard disks of the same type and partition status.

Recovery tools can be used NU tools such as software, the operation is very convenient. Of course, you can also use debug to operate, but the operation is cumbersome and has a certain risk.

Fault of partition valid mark error

An important part of the hard drive's main boot sector is the last two bytes: "55AA", which is a valid flag for the sector. When booting from a hard disk, floppy disk, or CD, the two bytes are detected and the hard drive is not recognized if it exists. This can be used for the entire hard drive encryption technology, the debug method for recovery processing. In addition, when the DOS boot sector does not have a boot flag, the system boot will appear as: "Mmissing operating System". The easiest way to do this is to use a common fix for the following DOS system.

Six, boot failure caused by DOS boot system

The DOS boot system consists of DOS boot sector and DOS system files. System files mainly include Io.sys, MSDOS. SYS, Command.com, where Command.com is a DOS shell file, can be replaced with other files of the same type, but by default it is a DOS boot prerequisite file. In the DOS system that Windows 95 carries, MSDOS. SYS is a text file that is required to start Windows, but does not use this file when you start DOS only. When a DOS boot error occurs, you can boot the system from a floppy disk or CD and use the SYS C: command delivery system to fix the failure, including the boot sector and system files that can be automatically repaired to the normal state.

Seven, 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 fat chains that specifies the address of the cluster 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, some tool software such as Nu and so on itself has 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 the full or partial contents of the file from it.

Viii. boot failure due to catalog table corruption

The catalog table records data such as the file name of the files on your hard disk, the most important of which is the starting cluster number of the file. Catalog tables Because there is no automatic backup feature, a large number of files will be lost if the directory is corrupted. One way to reduce loss is to search for * from the hard drive by using CHKDSK or ScanDisk program recovery. CHK file, because the catalog table is damaged only the first cluster number is lost, each *. CHK file is a complete file, change it to the original name can restore most of the files.

ix. Recovery of data when deleting partitions incorrectly

When you delete a hard disk partition with FDISK, the data on the surface of the hard disk has completely disappeared, and entering the hard drive when unformatted will appear as an invalid drive. If you understand how FDISK works, you'll know that Fdisk simply rewrote the contents of the hard drive's main boot sector (0 0 1 sectors), specifically deleting the hard disk partition table information, and the data for any partition on the hard drive has not changed. Can be modeled by the above partition Table error repair method, that is, find ways to restore the partition table data can restore the original partition and data. If you have already formatted the partition, you can restore the partition data in the following way after you have restored the partition.

Ten, incorrectly formatted hard disk data recovery

In the DOS High version state, the format formatting operation was established by default to restore the formatted disk information, in effect replicating all contents of the disk's DOS boot sector, FAT partition table, and 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 can be recovered by running the Unformat command. In addition, DOS also provides a miror command to record information about the current disk for reuse after formatting or deletion, and this method is also more effective.