Linux Notes: ISO Image Notes

1. The information presented here is intended for educational use by qualified computer technologists.
2. The information presented here is provided free of charge, as-is, with no warranty of any kind.

Introduction

This article is required because modern retail software outlets sell ISO burning software (for Windows or Macintosh) which satisfies the needs of most modern customers but not most computer technologists.

History

• The modern CD (optical Compact Disk) was first introduced in 1980 and initially targeted at the music industry (see: CD-DA)
• CDs quickly evolves to meet new demands as described by the Rainbow books (published by the IEC then later by the ISO) which includes CD-ROM for use by the computer industry
• Some companies violate industry standards for their own purposes (not illegal but also not wise)
• ISO-9660 was released in 1988 in order to get control of the ever-changing chaos.
• The ISO-9660 spec is extended a few times to meet the industry demands but I will only mention the two most popular:
  • Rock Ridge was championed by the UNIX industry to support long file names, long volume labels and UNIX-style file permissions
  • Joliet was championed by Microsoft to supports unicode character sets
• At the time it was decided that multi-use discs could be created where support for different ISO extensions could be written into the volume descriptor (so one primary and many optional alternates).
• But this turned out to be a big mess so most vendors moved beyond ISO-9660 to UDF (they probably wanted to called it universal file system but "UFS" was already being used elsewhere). But the problem here is this: not all older systems are able to navigate the multi-part volume descriptor so might default to the primary descriptor. Some of older technologies may include firmware-based BIOS
  Food-for-thought: The CD player in my 2010 Honda CR-V is able to play 1985 industry manufactured discs. On the flip side, no track titles or artist information is shown but the CD player is able to find the tracks.
• I doubt that anyone would have thought that optical media would be replaced with something else so soon but the rise of USB (universal serial bus) in 1995 soon enabled USB Flash Drives (also known as thumb drives) and ISO images can be written to these as well

2022: Problem on a +20 year-old system)

• Between 1985 and 2010, my employer purchased a huge number of Unix machines from Sun Microsystems
• Early systems employed the 32-bit SPARC CPU but most were replaced with systems employing the 64-bit UltraSPARC CPU
  • Note: Sun also built systems around the 32-bit x86 CPU as well as the 64-bit x86-64 CPU but that is not part of this story
• My employer still employs 20-year-old systems in order to run SPARC-dependant software (purchased from a third-party vendor that has gone out of business - and no access to the source code)
• A SunFire-150 recently died so I bought a replacement system online which was delivered without any CDROM media (Solaris-8 SPARC)
  • Note: there are no DVD drives in these units and all our original CDROMs are missing (walked away? or thrown away?)
• I attempted to purchase a Sun SPARC CDROM Kit from Oracle (acquired Sun in 2010) but they no longer sell museumware
• You will find a lot of original packages on eBay (where the prices range between $50 and $60) but be sure to read all the fine print which sometimes says something like this:
  "one original disc is missing but was replaced with a copy" (more on this problem in a moment)
• Rather than purchase media from eBay, I contacted another department (same company) to ask if they had any original media for a SunFire-150
• They did have originals but did not have any spare copies so agreed to send copies which did not work
• Report: disc-1 booted properly then Solais-8 began to install but disc-2 refused to mount
• Inspecting with software on Windows-10 revealed the following:
  • one of the welcome files on the copied disc claims to be expecting Rock Ridge
  • the Joliet volume names were truncated (so if Solaris-8 was attempting to mount by volume name than these disc would never work). The following came from file "identity"
    

    expected : SOL_8_HW703_SPARC_2
    actual   : SOL_8_HW703_SPAR

• Apparently, not all ISO coping software (colloquially known as a Music Ripper back in the days of Napster) seem to know about all the extensions to ISO-9660 including the three variations of Joliet and/or the unofficial variants of Rock Ridge

Reality Check

• I've visited numerous sites that claim that an ISO image file will reproduce the original disc exactly. This would only be true if the software used to copy the disk made exact copies of all original headers (Joliet, Rock Ridge, etc) but it appears to me that some products only read the Joliet extension if it exists (and some bad software will actually truncate the volume label to 12-characters). Burning a disk from this kind of file will only produce a windows-friendly product.
• IMHO the only solution forward is to acquire ripper software that copies everything properly. But what do you do if you receive a bad ISO Image file from a fellow employee?
• IMHO this is the only path forward:
  • extract all the files from the ISO file to a folder on your system (use third-party ISO software or 7-zip)
  • use third-party software (like PowerISO or BlackBox ISO 3) to create a new ISO file with the features you require (perhaps you want RockRidge but not Joliet )
  • use third-party software to inspect that file THEN burn it to a blank disc
  • I just tried this with PowerISO and it appeared to work
    • remember to set the volume name
    • remember to set the image file parameters to only support Rock Ridge
    • the burn to a blank

Apps

Reference Links

• https://handwiki.org/wiki/Rock_Ridge
• http://www.cdfs.com/cdfs-glos-rrip.html
• https://docs.microsoft.com/en-us/windows/win32/imapi/disc-formats (ISO-9660 - Joliet - UDF)
• http://littlesvr.ca/isomaster/resources/JolietSpecification.html
• https://unix.stackexchange.com/questions/67590/understanding-dao-sao-tao-and-raw-writing-modes-for-wodim-in-pract

  The CD-DA, CD-ROM, CD-R and CD-RW formats all store information in 2,352 byte sectors, divided into 98 distinct 24-byte frames. On CD-DA discs, each 24-byte frame holds two 16-byte audio samples, one for each stereo channel. The CD-ROM specification defines two sector modes, Mode 1 and Mode 2, which describe two different sector layouts. Both modes reserve the first 16 bytes for header information. Mode 1 uses an additional 288 bytes for error detection (32-bit CRC) and correction (276-byte RSPC).

   ------------------------------------------------------------------------------------------------------------------------
  | Format        |                                           2,352-byte sector                                            |
  |------------------------------------------------------------------------------------------------------------------------|
  | CD-DA         | 24-byte data frame (1) | 24-byte data frame (2) |            . . .           | 24-byte data frame (98) |
  | -----------------------------------------------------------------------------------------------------------------------|
  | CD-ROM Mode 1 | 12-byte sync pattern | 3-byte address | 2,048-byte data | 4-byte CRC | 8-byte reserved | 276-byte RSPC |
  | -----------------------------------------------------------------------------------------------------------------------|
  | CD-ROM Mode 2 | 12-byte sync pattern | 3-byte address |                        2,336-byte data                         |
   ------------------------------------------------------------------------------------------------------------------------