:: [DNG] reinstalling GRUB2
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Autor: Haines Brown
Data:  
Para: dng
Assunto: [DNG] reinstalling GRUB2
In the process of installing Ascii on a new HD in my box, I somehow
managed to break GRUB2 un the principal hard disk in the box, whhich
is /dev/sdb. When I boot /dev/sdb, I do not get its GRUB menu, but a
simple blinking cursor at the upper left. This usually indicates video
problems, but I have no problem with video when I use another means to
boot /dev/sdb.

To boot /dev/sdb I have to use reconnect SATA cables to all three
disks and use the BIOS boot menu to boot /dev/sda
or /dev/sdck. Then I use the boot menu on the disk to boot
/dev/sdb. /dev/sdb proceeds to boot without any problem.

To fix this, it went to reinstall GRUB2 on /dev/sdb. That effort
failed:

1. I insert an Ascii netinst key and select Advanced Options, Then I
select CLI rescue mode. I go though the installation steps to the
point I'm presented with a list of partitions. These are:

/dev/sdb1 This is /root
/dev/sdv2 This is broken out /boot
... [other partitions on sdb]
/dev/sdc1 [root on a HD with its SATA cable pulled]
/dev/sdc2 [ascii system]

/dev/sda also has its SATA cable pulled for the moment, but it
does not show up in the list of partitions. No idea why /dev/sdc shows
up.

2. The directions say to pick the root partition, and so I pick
/dev/sdb1.

3. Rescue mode next tells me that it sees I have /boot broken out,
and that to reinstall GRUB@ I need to mount it. So I say, Yes, mount it.

4. I am returned to the Rescue options menu. The choices are to pick a
differnet root file system, execute a shell, or to reboot. The only
other root file system is /dev/sdc1, but that's not where I want to
reinstall GRUB. I see no use for a shell. I don't see any option to
reinstall GRUB2.

In syslog, when I successfully boot /dev/sdb1 is the line:
Kernel command line: BOOT_IMAGE=/vmlinuz-4.9.0-9-amd64
root=UUID=fbc8d367-795c-48f2-a9c3-08029e1710e2 ro quiet

In /dev/sdb1/ are the symlinks:
initrd.img -> boot/initrd.img-4.9.0-9-amd64
initrd.img.old -> boot/initrd.img-4.9.0-8-amd64
vmlinuz -> boot/vmlinuz-4.9.0-9-amd64
vmlinuz.old -> boot/vmlinuz-4.9.0-8-amd64

vmlinuz-4.9.0-9-amd64 and initrd.img-4.9.0-9-amd64
are found in /dev/sdb2.

The file /boot/grub/grubenv is empty

In /etc/default/grub are:

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX=""


Haines Brown