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Since the update of grub needs manual intervention i am unsure where i had installed grub… My system is running since 2013 on a non UEFI system so had installed grub to a MBR, but which harddrive?
$:> LC_ALL=C lsblk
NAME LABEL FSTYPE SIZE FSAVAIL MOUNTPOINT UUID
sda 232.9G
|-sda1 Windows ntfs 39.1G D4104CE9104CD460
|-sda2 1K
|-sda5 VMs ext3 94.2G 30.5G /run/media/VMs 43baff62-585e-4802-b71b-3598be0bb2fb
|-sda6 swap 2.5G a6691214-03d7-4792-a31e-e6f49d7d35ab
`-sda7 Daten ntfs 97G 67.1G /run/media/Daten 4688B73734B455D1
sdb 119.2G
|-sdb1 arch_root_new ext4 19.6G f4633465-f70c-4b86-9e95-88ab9cac5773
`-sdb2 arch_home_new ext4 58.6G cc75b52d-0ac0-4240-b459-80cc905ae795
sdc 447.1G
|-sdc1 arch_root ext4 40G 19.1G / dfb61aac-71a9-412e-9528-730c63750354
|-sdc2 arch_swap swap 4G [SWAP] 676f657f-55cc-4423-a2ae-6d6b2bda8f62
|-sdc3 arch_home ext4 100G 40.7G /home e46de322-93a7-43d2-adeb-49031a288e28
`-sdc4 daten_neu ext4 303.1G 1bbf4bfb-d079-438f-a9fa-7ba935123c9f
sr0 1024M
sr1 1024M
As you can see there are three hard-drives where sdc is a SSD containing my main system. sdb is currently not in use.
How do i find out on which MBR of the harddrives i installed grub long years ago to get grub reinstalled on the same MBR when executing
grub-install --target=i386-pc /dev/sdX
?
Last edited by quiqueck (2022-09-02 05:56:03)
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The MBR will contain bootstrap code, which should contain GRUB-related texts. So see the output of:
sudo head -c 512 /dev/sdX | strings
If only one of the disks contains “GRUB”, you know which one is it.
Sometimes I seem a bit harsh — don’t get offended too easily!
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You can also check your BIOS which drive it is booting by default. It's likely that will be the GRUB drive. Just from a "that would make the most sense" perspective it would be /dev/sdc as that is apparently where your install lives, but yes the flexibility of GRUB would technically allow you to have the GRUB MBR bootstrap somewhere else (I think, not sure whether the bootstrap code can contain enough logic to search out a completely distinct drive for loading the rest of the config but who knows)
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Try if this helps in anyway.
file -s /dev/sdX
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Many thanks!
The MBR will contain bootstrap code, which should contain GRUB-related texts. So see the output of:
sudo head -c 512 /dev/sdX | strings
If only one of the disks contains “GRUB”, you know which one is it.
I used
sudo head -c 512 /dev/sdX | strings | grep -i grub
and this showed me that sdc is the harddrive where GRUB was installed.
You can also check your BIOS which drive it is booting by default. It's likely that will be the GRUB drive. Just from a "that would make the most sense" perspective it would be /dev/sdc as that is apparently where your install lives, but yes the flexibility of GRUB would technically allow you to have the GRUB MBR bootstrap somewhere else (I think, not sure whether the bootstrap code can contain enough logic to search out a completely distinct drive for loading the rest of the config but who knows)
Oh yes, probably. But rebooting the system to get into bios was to much waiting time
Try if this helps in anyway.
file -s /dev/sdX
This did not work, it showed for sdb and sdc the same output:
$:> sudo file -s /dev/sdc
/dev/sdc: DOS/MBR boot sector
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For me it gives more detailed answer:
> file -s /dev/sda
/dev/sda: DOS/MBR boot sector; GRand Unified Bootloader, stage1 version 0x3, boot drive 0x80, 1st sector stage2 0xa002d15
May be you had old grub. Check again after doing grub-install.
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I did the update of grub and ran
grub-install …
and regenerated grub.cfg, restart, all seems to be fine. Thanks again :-)
For me it gives more detailed answer:
> file -s /dev/sda /dev/sda: DOS/MBR boot sector; GRand Unified Bootloader, stage1 version 0x3, boot drive 0x80, 1st sector stage2 0xa002d15
I do not have such an output, it's still the same:
$:> sudo file -s /dev/sda
/dev/sda: DOS/MBR boot sector MS-MBR Windows 7 english at offset 0x163 "Invalid partition table" at offset 0x17b "Error loading operating system" at offset 0x19a "Missing operating system", disk signature 0x2fb82fb7; partition 1 : ID=0x7, active, start-CHS (0x0,32,33), end-CHS (0x3ff,254,63), startsector 2048, 81920000 sectors; partition 2 : ID=0x5, start-CHS (0x3ff,254,63), end-CHS (0x3ff,254,63), startsector 81931561, 406460504 sectors
$:> sudo file -s /dev/sdb
/dev/sdb: DOS/MBR boot sector
$:> sudo file -s /dev/sdc
/dev/sdc: DOS/MBR boot sector
Grub version:
$:> LC_ALL=C pacman -Qi grub
Name : grub
Version : 2:2.06.r322.gd9b4638c5-3
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