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What do beginners in cloud computing have to face? How to troubleshoot Linux system faults? Linux is a commonly used free and open source operating system in the market, and it is also a good helper in the daily work of cloud computing operators. However, many beginners of cloud computing are at a loss in the face of Linux system failures, and then Qianfeng editor will share with you several common Linux system failures and their troubleshooting methods.

1. Forget the root password

In single-user mode, Linux does not require a root password (Red Hat systems do not need a root password, but SuSe does. Different Linux systems are slightly different to understand how to enter single-user mode when the system fails to boot into multi-user mode. The steps are as follows:

1) during the startup process of the system, the start interface will appear and press any key to enter the GRUB menu option.

2) press the "e" key to edit the GRUB boot menu options, press the "e" key after the GRUB screen. Move down to the kernel line with the arrow keys and press the "e" key.

3) add single at the trailing cursor, press enter to return to the previous screen, press the "b" key to boot, the system will automatically enter single-user mode, if you want to change the root password, execute the command: sh-3.1# passwd root.

After the change is successful, execute the command exit to exit and restart. Correct many problems that prevent the system from starting normally in single-user mode, such as disabling services that may stop the system, such as disabling the Samba service, you just need to execute: sh-3.1# chkconfig smb off the next system boot will not start the Samba service.

2. GRUB option setting error

"Error 15" shows that the system cannot find the kernel specified in grub.conf. This is a mistake that many novice Linux users are easy to make when modifying GRUB settings. When this black screen prompt appears, pay attention to observe the error message and fix it.

GRUB boot error message, we observed that because of the typing error, the kernel file "vmlinuz" was typed as "vmlinux", so the system could not find the kernel executable file. You can press any key to go back to the GRUB editing interface, correct this error, enter and save, press the "b" key to boot normally, of course, don't forget to modify the error here in the grub.conf file after entering the system.

3. Hard disk sector disorder

The most common problem encountered in the startup process is that the hard disk may have bad tracks or sector confusion (data damage), which is mostly caused by abnormal power outage and abnormal shutdown.

When this problem occurs, when the system starts, the screen will display: Press root password or ctrl+D:

At this point, enter the root password system automatically into single-user mode, enter: fsck-y / dev/hda6

(fsck is the file system detection repair command, "- y" sets the error detected to automatically repair, / dev/hda6 is the hard disk partition where the error occurred, be sure to change this parameter according to the specific situation).

After the system is repaired, restart it with the command "reboot".

Of course, in addition to the above, there are many common Linux system troubleshooting methods, such as when the system can not even enter the single-user mode or the boot problem that can not be solved by the GRUB command line, we can use Linux rescue mode for troubleshooting. Only by fully understanding the boot process of Linux, can we effectively judge and deal with the fault.

If you want to engage in cloud computing operation and maintenance, it is a good choice to participate in professional study. Quickly become a cloud computing talent with both theory and practice, so that he can be qualified for the positions of operation and maintenance engineer, cloud computing engineer and Web*** test engineer.

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