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. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/56471eb84fb7089d3745749b71e15ba5.squir...@nonada.if.usp.br
