Analysis and Solution of system startup faults under RedHatLinux5

During RedHatLinux5 system startup, the MBR Master Boot Record, GRUB boot menu, system initialization configuration file, and partition mounting configuration file are involved, faults in any stage may cause system startup failures. Today's experiment simulates these faults and then solves them. I. an MBR slice fault first introduces the MBR slice. It is the first slice (512 bytes) of a physical hard disk and consists of three parts: 1. the main Bootstrap code, accounting for 446 bytes; 2. hard Disk Partition Table DPT, 64 bytes

During the startup of the Red Hat Linux5 system, the MBR Master Boot Record, GRUB boot menu, system initialization configuration file, and partition mounting configuration file are involved, faults in any stage may cause system startup failures. Today's experiment simulates these faults and then solves them.

I. MBR sector failure

The MBR sector is the first sector (512 bytes) of a physical hard disk. It consists of three parts: 1. the main Bootstrap code, accounting for 446 bytes; 2. hard Disk Partition Table DPT, which occupies 64 bytes; 3. AA55H indicates the end of the primary Boot Sector. The MBR Boot Record is located in the MBR sector. When the MBR sector fails, the boot menu may not be available or the system cannot be loaded because the correct partition location cannot be found, when the host is booted through the hard disk, it is likely to enter the black screen status. Next, we will simulate the MBR sector backup, destruction, and repair process through experiments:

1. Backup: Back up the MBR sector of the first hard disk (sda) to the sdb1 partition of the second hard disk.

2. Simulate damage to the MBR sector: Read 512 bytes of data from the null Device File zero and write the data to the first hard disk sda, thus damaging the data in the MBR sector.

After the preceding operations are completed, the system will be restarted and a message indicating that the available Operating system cannot be found. Therefore, the host cannot be started. (For example)