[Info-vax] InfoServer 150

[John E. Malmberg]

On 1/27/2019 8:12 AM, Bob Wilson wrote:
> On Sunday, January 27, 2019 at 8:32:18 AM UTC-5, Hans Vlems wrote:
>> It’s just bits, no problem there. Creating an image backup from a
>> disk still won’t work when that file gets written to a cdrom. The
>> output of dd or backup/physical may be used as input for cd writer
>> programs on Windows. And if necessary the filetype iso should be
>> appended to the filename.

> I agree (re: "it's just bits")...a "ISO image" is just a
> sector-by-sector copy of physical media, which may or may not be a
> ISO-9660 volume. Sort of like a spiral-read of the volume from block
> 0 - maxblock.
You are getting the terms wrong, and that can cause problems.

A disk image is a block by block image of the disk contents.

An ISO image is an image that conforms to the ISO-9660 standard.

Several disk blocks of a disk images are not used with ISO-9660 media. 
This is intentional to allow dual format disk images by the ISO committee.

The issue that the hobbyist disks disk images have a .iso extensions yet 
are not burned as ISO images when making CD-ROM is a frequent cause of 
confusion on the https://www.openvmshobbyist.com/forum .

While some CD-Burner programs may treat disk images and ISO images the 
same, many now do not.

Especially GUI based ones that validate the file contents.  If they do 
not find the ISO structure in an alleged ISO image, they can default to 
creating an ISO file structure and putting the disk image in it as a file.

And for disk images that are dual format ISO and other format, some 
burner programs when you tell it that the source is an ISO image, may 
only burn the ISO portion of the image, and not all of the disk contents.

So you need to find disk burning software that supports burning image 
files, not just ISO images.

Only one of the hobbyist disk images have ISO-9660 content, the IA64 
system install disk.  And that one is dual format.  The rest are disk 
images.

Due to their age, I suspect that the Inforserver disk images are not iso 
images, even though that they may be named as such.

HPE/VSI has an internal port of mkiosf that is used as part of creating 
that disk image.  It may not be usable for making other types of images, 
as stuff that was not needed for making the IA64 boot was removed if it 
caused compile/link issues.  (There is a layer in the source that is a 
wrapper for all the syscalls that was removed)

This was needed for creating the El-Torito DVD boot required by the 
Itanium console, which existing ports of mkiosf did not support.

If someone is motivated to properly update the port of mkiosf to VMS, it 
would be nice to add dual format ISO/OD5 support natively.  With that 
support, when you mount the disk as ISO-9660, you would also see all the 
VMS files.  That would likely involve making sure that the trans.tbl 
files are generated for full compatibility.

Regards,
-John