Re: Boot from 4TB USB jhard drive

[Emilio Lazo Zaia]

On 20/03/16 00:35, Andrei Borzenkov wrote:
> (...)
> Create rescue image that can be used to boot off CD/USB
>
> pkgdatadir=$PWD ./grub-mkrescue -d grub-core -o /tmp/grub.iso
>
> This creates ISO image suitable for both CD and HDD boot. If using USB
> stick, just dd this image on full stick. When booting from it, you will
> end in GRUB command prompt.
Dumped into a USB stick...
> Check what
>
> ls -l
> in GRUB CLI says. What sector size GRUB detects for your disk? Does GRUB
> see partitions on your disk? Do they look reasonable (size, offset)? If
> yes, try
It says "Device hd2: No known filesystem detected - Sector size 4096B - 
Total size 3906984960KiB"

Partitions are not detected! In the previous test (GRUB 2.00-7) it 
doesn't show the sector size but the sector size it detects is 512B 
because of total sectors and partition offsets. In that test, ls -l says:

Device hd2: No known filesystem detected - Total size 7813969920
    Partition hd2,gpt2: No known ... - Starts at 2048 ...
    Partition hd2,gpt1: No known ... - Starts at 64 ...

Total size of 7813969920 sectors with 512 bytes per sector is also 
3906984960KiB. Partition 1 starts at sector 64 (assuming 512B sectors) 
is the same as it starts at sector 8 (4096B sectors, as gpart shows). 
The same applies to partition 2, which starts at sector 2048 on 512B 
units, or 256 on 4096B units.
> insmod lvm
> ls -l
>
> again. Does GRUB detect LVs?
Nein. It doesn't detect LVs with the iso hybrid image I dumped into an 
USB stick, but it detect LVs and load kernel with GRUB 2.00-7 installed 
on laptop's hard drive.
> Do you have serial port (RS-2323) on your system and another system that
> can be used to connect to serial port? This would make capturing output
> much easier.
I'm sorry, I don't have serial ports.

Emilio.