This software does not actually write to CD-R or DVD-R devices. Volumes created as disc images or entire magnetic disks should be transferred to CD-R or DVD-R using an Infoserver or various tools that run directly on VMS.
Revision/Update Information: This is a new manual
Operating System and Version:
VAX/VMS Version 6.1 or higher
Alpha VMS Version 6.1 or higher
Software Version: LJK/CDROM V1.0
The following are trademarks of LJK Software:
The following are trademarks of Hewlett-Packard Company:
| Contents | Index |
LJK/CDROM has two major capabilities:
If you are interested in making casual use of LJK/CDROM, you should concentrate on the Chapter 1, Getting Started.
This manual is intended for an individual who is interested in the creation of ISO-9660 and related Volume structures.
There is no particular requirement that the individual using LJK/CDROM be a VMS system manager or have privileged access to the machine on which LJK/CDROM is installed, but in some cases a CDROM or magnetic disk device might need to be protected so as to allow the LJK/CDROM user to mount the device /FOREIGN. A VMS ACL is usually preferable for that.
LJK/CDROM is designed to comply with the following standards:
Of course LJK Software welcomes citation of particular sections of the relevant standards within bug reports submitted as described in Appendix B, Bug Reports, but going to that length is not required for most bug reports.
Within this LJK/CDROM Reference Manual the term "ODS-n" means either VMS ODS-2 or VMS ODS-5, since the two format are almost the same as compared to ISO-9660.
Within this LJK/CDROM Reference Manual the term "disk" means means a fixed disk (typically magnetic) while the term "disc" means a removable disc such as CDROM, CD-R, DVD or DVD-R.
Within this LJK/CDROM Reference Manual unexpectedly capitalized terms within normal text paragraphs have specific meanings in the context of ISO-9660 and related standards. Such terms are defined in ISO-9660 Glossary. For instance, the term "volume set" might mean an ISO-9660 Volume Set or an ODS-n volume set, but when capitalized as "Volume Set" within this document it always means an ISO-9660 Volume Set.
This is a new product.
Serious users of LJK/CDROM will need to read subsequent chapters of this manual to understand the full capabilities of the program. But casual users might be able to succeed by reading just this chapter, at least to get started.
In particular, if you are using the no-charge license1 to verify the integrity of ISO-9660 CDROMs or disc images formatted with other tools you will be able to get by with just the following section, Verifying ISO-9660 Formatting, so long as you do not encounter any errors.
1 As described in Appendix D, Licensing, no Product Authorization Key (PAK) is required for the no-charge license. |
1.1 Verifying ISO-9660 Formatting
You can use LJK/CDROM to check the following formats written either by LJK/CDROM or by another program:
LJK/CDROM VERIFY ddcu: |
The command to verify the integrity of a disc image is:
LJK/CDROM VERIFY ddcu:[dir.subdir]file.ext |
If you receive error messages with the command LJK/CDROM
VERIFY, you should read the discussion
at the start of Chapter 7, Verifying a Volume, to help you come to a decision regarding
how serious those errors are in your environment.
1.2 Formatting a CDROM Volume
You can use LJK/CDROM to write the following formats:
with just a simple command.The command to write to an entire magnetic disk is:
LJK/CDROM WRITE ddcu: source-filespec-1,source-filespec-2,... |
The command to create a disc image is:
LJK/CDROM WRITE target-filespec source-filespec-1,source-filespec-2,... |
The LJK/CDROM WRITE command takes the target file specification before the source file specifications because the source file specifications are optional. |
You must use "subsystem mode" described in Section 9.2, Command Formats, to issue commands like CREATE HIERARCHY before the WRITE command to write a Volume using any of the following formats:
This chapter explains the general nature of the ISO-9660 standard as preparation for making effective use of LJK/CDROM.
2.1 Why would one use ISO 9660 CDROMs on VMS?
Of course exchange of data with other operating systems is the first reason most people consider using the ISO-9660 format on VMS, but that must be tempered by certain considerations:
| Reasons to create ISO-9660 Volumes | |
|---|---|
| Characteristic | Description |
| Optimized for CDROM and DVD | Structures internal to the ISO-9660 format speed up access to data on a medium where seeks are relatively slow compared to transfer times. By contrast, the ODS-n data structure was designed for a read-write environment supporting careful update so that data would not become inconsistent in the event of a system crash. ISO-9660, as a format not allowing updates once a Volume has been written, is free of those needs. |
| Volume Switching | ISO-9660 support on VMS is designed to allow mounting of just some of the members of a Volume Set, switching to other members only if their data is required. This allows support of extremely large (up to 65535-member) Volume Sets without excessive numbers of drives. |
| Adding to a Volume Set | The ISO-9660 standard is designed to allow easy addition of new Volumes to an existing Volume Set, with the later Volumes containing full directory information about contents of the earlier Volumes. ODS-n, by contrast, was designed for read-write disks and requires the ability to write to older Volumes---not quite the model for CDROM and DVD |
| Reasons to create ODS-n Volumes | |
| Characteristic | Description |
| A simpler MOUNT command | One must specify the /UCS_SEQUENCE="(B" qualifier to mount an ISO-9660 Volume whose Directory Identifiers and File Identifiers contain dollar-signs or dashes or the /UCS_SEQUENCE="-A" to mount an ISO-9660 Volume whose Directory Identifiers and File Identifiers use the full ODS-5 character set. |
| CDROM support back to VMS 5.0 | ISO-9660 format is not supported on VMS versions prior to V6.1 (Alpha) or V6.2 (VAX). |
| Booting from CDROM | The VMS operating system itself will not boot from an ISO-9660 format disc. While most people do not need to write discs from which VMS will boot, for those who do, the need is critical. |
An initial reaction might be to suggest use of a hybrid volume format, containing both ISO-9660 and ODS-n directory structures. That would merge some advantages of the two formats, but with certain drawbacks:
In summary, a hybrid ISO-9660/ODS-n volume (which LJK/CDROM
does not currently support), would be useful for single volumes but not
for volume sets.
2.2 The Nature of ISO-9660 Volumes
An ISO-9660 Volume bears certain similarities to a traditional
VMS ODS-n volume, but also has certain differences.
2.2.1 Hierarchies
In recognition of the reality that different operating systems will have different needs, an ISO-9660 Volume can have a variety (limited only by disc space) of Hierarchies, each consisting of a user-visible directory tree and additional metadata that may or may not be apparent to the user. This is a considerable departure from ODS-n, where there is a single hierarchy based at the master file directory (MFD, [000000]). All directories can be found in that one tree on ODS-n.
One prominent use of these separate Hierarchies is to provide different Character Sets for diverse computing environments. One Hierarchy might have a limited structure restricting File Identifiers to uppercase alphanumeric characters while another Hierarchy had diverse characters. These various Hierarchies can have their directory entries point to the same File data, sharing it in the same way that an alias directory entry does on a traditional ODS-n disk. While Files can be shared between Hierarchies, there is no requirement that a File be accessible from all Hierarchies.
Figure 2-1 Multiple Hierarchies Pointing to the Same Files
ISO-9660 has nothing comparable to an alias entry that points to a directory. Directories are not shared at all between Hierarchies, since the entries within each Directory must conform to the Hierarchy to which that Directory belongs.
2.2.2 File Identifiers
ISO-9660 specifies File Identifiers quite similar to those for VMS,
consisting of three parts and two separators:
ISO-9660 Directory Identifiers, on the other hand, consist of a single field,
up to 31 characters in length. ISO-9660 Directory Identifiers have no extension
2 or version components.
2.2.4 Character Sets
Every Hierarchy on an ISO-9660 Volume has a specific
Character Set allowed for metadata. That Character Set is known as the
"C-Characters" and is defined for the Hierarchy
according to
the ISO-2022 standard using a set of Escape Sequences.
2.2.4.1 D1-Characters
A subset of the "C-Characters" are called D1-Characters and are the only ones allowed for certain metadata fields:
A different subset of the "C-Characters" are called A1-Characters and are the only ones allowed for the remaining character metadata fields:
2 An extension is allowed in a Directory Identifier by the Microsoft Joliet format, which is just one of several reasons that Joliet does not really conform to the ISO-9660 specification. |
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