[Debburn-devel] Write iso/isohybrid on pendrive:problem

[Thomas Schmitt]

Hi,

antispammbox-debian wrote:
> Then isohybrid does not produce a true hybrid file, because once written,
> cannot re-format the space free on usb!

Well, firstly the isohybrid program of ISOLINUX is The Original.
The isohybrid functionality of xorriso was implemented under the
guidance of the ISOLINUX main developer. Insofar, both are "true".

The partition offset feature is out of the reach of the isohybrid
program, because it operates on an existing ISO 9660 image and has
no means to create a second superblock and directory tree for
mounting at a non-zero partition start.
xorriso creates the ISO image and thus is able to create both
structures of meta data. Then it makes sense to move the partition
start to block 64.
(Program isohybrid could check for an existing second set of meta
data, though.)

After all, we do not yet know whether your problem is really
caused by the difference of partition start. An experiment would
be needed.
Either move partition start of the original ISO image to 0,
or move the start of the isohybrid result to 64.
This would cause a change in behavior under Gparted, if my theory
is true.

If partition start 0 is the reason for Gparted's refusal, then it
is a peculiarity of Gparted, not of isohybrid.
Gparted does have requirements towards the existing partition table
on the medium.


> But the problem then, is, how to create isohybrid file,  that
> allows  to re-format free space on usb.

This text describes how to fix a size overlap by help of sfdisk:
  http://gparted.sourceforge.net/h2-fix-msdos-pt.php

The procedure to set the partition start to 64 (not 63 !) should
be quite similar.


Have a nice day :)

Thomas