Re: Installation failed - and failed again...
Brian wrote:
> On Sun 03 Mar 2013 at 18:07:26 -0300, Joao Luis Meloni Assirati wrote:
>
>> > Write a netinst image to two USB devices. Boot from one device and
>> > install to the second one. Try text and GUI modes. It's about an
>> hour's
>> > work at most.
>>
>> But will this happen even if one formats the partition holding the iso?
>> What if the installation proccess is done normally, the target device
>> that
>> happens to hold the iso is partitioned and all the partitions are
>> formatted? When grub gets to be installed, in the last installation
>> step,
>> all the information that an iso existed before is gone, or no?
>
> When the isohybrid ISO is written to to the drive the information about
> the iso9660 filesystem is put within the first 65 sectors of the drive.
> If fdisk is now used to partition the drive the first partition starts
> at sector 2048. Everything beyond this sector is destroyed but sectors
> below number 2048 are left intact. The drive is now useless as a device
> to boot Debian but information about the iso9660 file system is left
> intact.
Wow, of course. The iso image must be installed in the begining of the
disk, which includes the partition table and the mbr, not in the first
partition.
> fdisk leaves space at the beginning of the drive because GRUB requires
> it to embed part of itself there. But GRUB will not go there because it
> thinks it is overwriting data on the disk when it detects the iso9660
> signature. This is by design.
This is clearly a bug, because the disk has a partition table and
therefore there is no useful data before the first partition.
> D-I uses partman for partitioning. It too leaves an embedding area which
> contains the iso9660 data sector. The solution is to remember to do
>
> dd if=/dev/zero of=/dev/sdX count=65
>
> before partitioning.
But this will destroy the partition table, which is not right if you have
other operating systems or partitions containing data. Maybe 'grub-install
--force <device>' would suffice?
>> Anyway, it must be said that you did an impressive investigation with
>> very
>> scarce resources to say the least, Brian!
>
> Thanks. I cheated though! I had already encountered the bug some time
> ago and the reported behaviour in this thread is very, very similar to
> it.
Of course you deserve congratulations. You had to guess among the various
phony bug reports. It was some kind of psychoanalysis. Your patient still
did not achieve catharsis, though.
João Luis.
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