Linux Failure simulation

Linux Failure simulation

1, MBR damage

1.1. With host: (slightly)

1.2. Use emergency rescue mode: System installation CD

Boot:linux Rescue

/mnt/sysimage

To create a device file manually: Mknod

[Email protected] ~]# fdisk-l
disk/dev/sda:113.8 GB, 113816633344 bytes
255 heads, Sectors/track, 13837 cylinders
...
[[email protected] ~]# dd if=/dev/sda of=/root/mbr.backup count=1 bs=512 # backup before test
1+0 Records in
1+0 Records out
Bytes (+ B) copied, 0.00372704 seconds, 137 kb/s
[Email protected] ~]# Ll/root/mbr.backup
-rw-r--r--1 root root 9 08:27/root/mbr.backup
[[email protected] ~]# dd if=/dev/zero of=/dev/sda count=1 bs=300 # clear HDD Front 300b
1+0 Records in
1+0 Records out
Bytes (B) copied, 6.3003e-05 seconds, 4.8 MB/s
[Email protected] ~]#

The workaround is as follows : Start the installation CD

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CD-ROM startup input: Linux rescue

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2. Grub corruption or file loss

[[email protected] ~]# mv/boot/grub/grub.conf/root/ # Erase Grub File
[[Email protected] ~]# Sync

Post-boot appears as follows:

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The solution is as follows:

grub> Root (hd0,0)

Grub> Kernel/vmlinuz-ro Root=/dev/sd7 # The root path is/DEV/SD7 when installing the system

Grub> initrd/initrd-

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3. Kernel Panic: Kernel panic

3.1. Default level is set to 0 or 6: Enter single user mode, modify Inittab file

3.2. No boot files in/ETC/RC.D/RC3.D: Enter single user mode, create new related files

3.3. SendMail: The preparation file timestamp check failed:

3.3.1. Turn off the service in single-user mode;

3.3.2. Time stamp in single-user mode repair;

3.3.3. Press " I " key to enter interactive mode at startup, manually specify whether all services are started;

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4. File syntax error or logic error in/etc/rc.local: Change file in single-user mode

5. Path variable error: do not exit the interface first

Backup files under/etc, (version control program: Svn,git developer)

Export Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin

6. mingetty file lost: Go to Single user mode, network or CD-ROM mode reinstall

Bash lost:/bin/bash Rename simulation lost

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Can not be shut down in the boot failure;

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Workaround:

CD-ROM boot into emergency mode and reinstall bash using the installation files on the CD

6.1. No Network: Mount CD

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6.2 A network: Copy bash installation files over the network

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Linux Failure simulation