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Восстановление Grub

Представьте себе, по какой-либо причине у вас есть другие дрянные операционной системы, установленной рядом с Debian. И по какой-то причине вам придется его переустановить, потому что он на самом деле сломан. Опять же, представьте себе, у этой этой дрянной ОС получилась дрянная установка и она переписала загрузочную запись MBR, полностью завладев компьютером. Что дальше? Переустановка Debian? Нет.

In any case, you can use SuperGrub, a boot utility that can restore and repair overwritten and misconfigured GRUB installs or directly boot various operating systems.

Standard procedure

The Debian Installer (DVD, netinst CD, floppy, netboot, etc.) can be used to rescue systems, for example if they fail to boot after an upgrade. You should read and follow the instruction "Recovering a Broken System" section of the Installation Guide1 (look for it in the index) [link to stable/i386].

Troubleshooting : 'grub-install /dev/sda' failed.

If D-I's "Reinstall GRUB boot loader" option fails, with error message

Unable to install GRUB in /dev/sda
Executing 'grub-install /dev/sda' failed.
This is a fatal error.

Also, the d-i log console (Alt-F4) displays

grub-installer: /dev/scsi/host0/bus0/target0/lun0/disc does not have any corresponding BIOS Drive

You can still use the following method to reinstall GRUB. Choose "Execute a shell in Your root partition" in the d-i rescue menu.

Locate your root partition :

fdisk -l

Disk /dev/sda: 39.9 GB, 39996820992 bytes
255 heads, 63 sectors/track, 4862 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1         111      891576    7  HPFS/NTFS
/dev/sda2             167         230      514080   82  Linux swap
/dev/sda3             231         784     4450005   83  Linux
/dev/sda4             785        4862    32756535    f  W95 Ext'd (LBA)
/dev/sda5             785        4862    32756503+  83  Linux

Reinstall GRUB bootloader (grub manual)

If you have grub-legacy 2 and your root partition is /dev/sda3 then you can re-install grub in the MBR of your hard drive by typing the following commands :

sudo grub
grub>root (hd0,2)
grub>setup (hd0)
grub>quit
exit

Note that in grub-legacy (hd0,2) is the third partition.

Then choose "Reboot the system", everything should be fine.


CategoryBootProcess

  1. http://www.debian.org/releases/ (1)

  2. If you have stage1, stage2 and menu.lst files in /boot/grub/ then you probably have a working grub-legacy. If you have several *.mod files and a grub.cfg file in /boot/grub/ then you have the new grub. (2)