[Info-vax] InfoServer 150

[Bob Wilson]

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.

I make documentation discs (CDs and DVDs) on my Mac, which I burn to ISO-9660 volumes...I can take those ISO-9660 discs and MOUNT/FOREIGN -> COPY ddcu: FOO.ISO them on a VMS system. If I do LD CONNECT of FOO.ISO and MOUNT the LDAn: device VMS recognizes it as a ISO-9660 volume (ODS-3 or -4, don't remember which).

Some disc burning software insists that the file type be .ISO to convince it to do a disk-image-to-disc (we used to use .IMG as the file type, but switched to .ISO to save a step to RENAME the file).  

On Windows 7 right clicking  on a .ISO file gives the option to "Burn disc image", which doesn't work with non-ISO-9660 .ISO files...for a VMS/ODS .ISO file it throws a "The selected disk image isn't valid" error. Anecdotally I'd say it's trying to verify that the .ISO file contains a ISO-9660 volume (to verify I downloaded  a Ubuntu .ISO distribution to my Windows 7 system and was able to right-click & "Burn disc image" successfully).