Linux Note 2-11 System Recovery

11. System Recovery ***********

# #系统启动流程 # #

Power

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BIOS (in read-only storage on the motherboard, basic input or output system)

function, hardware detection, activation hardware

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Grub System boot (grub boot divided into two stages)

1) Stage 1 MBR (Master boot record) master boot record 0 tracks on hard disk, one sector, 446 bytes

*) dd If=/dev/zero Of=/dev/vda bs=446 count=1 can empty MBR

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*) go to save mode, perform chroot/mnt/sysimage switch to real/environment,

and execute GRUB2-INSTALL/DEV/VDA

Booting from the network card

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2) Phase 2 Grub File boot phase

Locate the/boot partition

Read /boot/grub2/grub.cfg

file lost,grub2-mkconfig >/boot/grub2/grub.cfg

Booting from the network card

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boot kernel, read-only mount /device

Testing equipment

Initialize the device driver

Enter the system initialization phase

Kernel is missing, the new kernel installation package can be resolved

RPM-IVH kernel-xxxxx.rpm--force

Or you can add the missing files

Rpm2cpio kernel-xxxxx.rpm | Cpio-id // decomposition file

Booting from the network card

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System initialization phase

system initialization phase load INITRD mirror

Open Initialization Process SYSTEMD

Start SELinux

Load Kernel parameters

Initialize the system clock, keyboard, host name

re-read/write mount /device

activating RAID,LVM

Activate quotas

start All services in the multi-user.target.wants

If the boot service configuration is wrong, you can press "E" in the Startup selection screen , modify the boot configuration, and then restore the correct configuration.

For example, if you start the boot by default, link to Reboot.service. The system will restart after booting, in the Boot selection screen, select "E", the kernel boot option to fix RW, and in the last

add rd.break. When startup executes here, the system exits and modifies the boot configuration file in the resulting shell

Booting from hard disk

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Turn on the Virtual Console

Start graphics

initramfs-' uname-r '. img

lost by: mkinitrd initramfs-' uname-r '. img ' uname-r ' recovery

or mkinitrd initramfs-$ (UNAME-R). IMG $ (UNAME-R)

Uname-r--View system version number

Booting from the network card

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Note: If the contents of/boot/partition are all lost

Install GRUB2 First , then reload the kernel, and finally restore the/boot/grub2/grub.cfg file

Booting from the network card

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Change Password

Booting from hard disk

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Linux Note 2-11 System Recovery