Mounting ISO 9660 Volume Sets and Groups

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HP OpenVMS System Manager's Manual, Volume 1:...

Managing Storage Media

Expanding Volumes Dynamically

Mounting Tape Volume Sets

Mounting ISO 9660 Volume Sets and Groups

To access an ISO 9660-formatted CD-ROM, you can mount disk volumes in two ways:

Directly, using the Mount utility (MOUNT)

Indirectly, using the DCL command MOUNT

The Mount utility (MOUNT) builds the I/O database structures that are needed to access ISO 9660 directories and files. MOUNT also verifies the presence of an appropriate ACP to perform $QIO functions specific to ISO 9660. Currently, you cannot mount ISO 9660 media as a system disk. Refer to the HP OpenVMS System Management Utilities Reference Manual for details.

For more information about ISO 9660 volume structure on CD-ROM media, refer to the Guide to OpenVMS File Applications .

Mounting ISO 9660 Volume Sets

ISO 9660 supports volume sets of up to 65,535 volume set members. At any one time, users can mount a 255-member subset of the total volume set of 65,535.

If your volume set is greater than the number of CD-ROM readers available to you, you can swap volume set members, for example, as you might when you have a single reader with multiple volume set members.

Mounting ISO 9660 Volume Groups

A volume group consists of one or more consecutively numbered volumes within a volume set. Affinity between the members of a volume group is established by the fact that the volumes are recorded together and are subject to the same maximum-volume-set-size parameter.

Each volume in a volume group contains information describing all the files and directories recorded on all of the volumes in the volume set, up to and including the members of its volume group. For example, assume that a volume set includes two volume groups:

The first group includes Volumes 1 and 2, which were recorded together, prior to the second group.

Volumes 1 and 2 each contain information only about their volume group; they have no information about the volumes in the second volume group.

The second group includes Volumes 3, 4, and 5, which were recorded together at a later date.

Volumes 3, 4, and 5 each contain information about all of the volumes in the volume set, including Volumes 1 and 2.

How to Perform This Task

When you mount a volume set, you must first mount a member of the highest-numbered volume group (the most recently recorded group--in the example, Volume 3, 4, or 5), because only a member of the highest-numbered group has the information needed to mount all members of the volume set.

If you do not follow this requirement, you must dismount all of the volumes and start again by specifying a member of the highest-numbered volume group as the first volume to be mounted.

Handling Partially Mounted ISO 9660 Volume Sets

OpenVMS systems support partially mounted ISO 9660 volume sets. Data is usually read from all mounted volumes in a manner that is transparent to the user program.

When a volume-set member is not mounted because the volume set is partially mounted, OPCOM sends a message to the OPERATOR class DISK requesting that the unmounted volume be mounted. If you do not honor the request within a specified time period, or if you do not enable the option to provide for dynamically mounting a volume, the I/O process fails, and an error message is issued.

Mounting ISO 9660 Volumes Using SVDs

All ISO 9660 volumes contain a Primary Volume Descriptor (PVD) that uses ASCII (ISO 646-IRV) as the character set. Both ISO 9660 and OpenVMS file naming conventions use the same subset of ASCII characters when displaying the directories and file names of a volume.

In addition to mounting ISO 9660 volumes using the default PVD, you can also mount ISO 9660 volumes using a Supplementary Volume Descriptor (SVD).

This capability allows access to an ISO 9660 volume with directories and file names containing characters from character sets other than the ISO 9660 limited set, which includes only A through Z, underscore (_), period (.) and semicolon (;).

The author of the ISO 9660 volume set must record the volume with the required PVD, and optionally with one or more SVDs. Each SVD must contain a unique volume label and escape sequence.

Use the following command syntax to mount an ISO 9660 device using an SVD:MOUNT device-name volume-label /UCS_SEQUENCE=escape_sequence

where:

device-name
Specifies the physical device name or logical name of the device on which the ISO 9660 volume is to be mounted.

volume-label
Specifies the SVD volume label obtained from the author's label on the CD-ROM.

escape-sequence
Specifies the escape sequence obtained from the author's label on the CD-ROM.

If an ISO 9660 volume contains SVDs with no escape sequence specified, the default character set is assumed to be ISO 646 (ASCII). This default character set allows the use of the file specification character set supported by OpenVMS, which includes these additional characters: dollar sign ($) and dash (-).

Use the following command syntax to mount a volume using the SVD volume label when no escape sequence is specified:MOUNT device-name volume-label /UCS_SEQUENCE=""

If an ISO 9660 volume contains SVDs with escape sequences other than ISO 646, ISO 2022 or ISO 13646 (formats on CDs), the character set might not interoperate with the OpenVMS file specification syntax.

Refer to the Guide to OpenVMS File Applications for more information about ISO 9660 volume structure on CD-ROM media.

Handling ISO 9660 Restrictions

ISO 9660 Restrictions describes problems and restrictions that apply to OpenVMS support of the ISO 9660 standard and explains how to resolve them.

Table 15 ISO 9660 Restrictions
Media Affected Description and Resolution

Volume Labels
These can contain from 1 to 32 characters. The first 12 characters are used to produce a unique volume identity. If the label is not unique within the first 12 characters, the volume will not mount and the following error message is displayed:
%SYSTEM-F-VOLALRMNT, another volume of the same label already mounted

How to resolve this problem:

Mount the volume specifying a different volume label and use the /OVERRIDE=IDENTIFICATION qualifier. This will override the volume's label so as not to conflict with the label of an already-mounted volume.

Volume Set Labels
These can be from 1 to 128 characters in length. The first 12 characters are used to produce a unique volume set identity. If the volume set label is not unique within the first 12 characters, the volume will not mount and one of the following error messages will be displayed:
%SYSTEM-F-VOLINSET, volume is already part of another volume set %MOUNT-F-DUPRVN, duplicate volume number already mounted

How to resolve this problem:

Mount the volume specifying a new volume set label with the /BIND=volume-set-name command qualifier.

Volume Label and Volume Set Label Duplication
The first 12 characters of both the volume label and the volume set label are used to produce different lock manager resource names, which are then used to coordinate volume and volume set associations. If both the volume label and the volume set label are the same (within the first 12 characters, including null labels), a lock manager deadlock error occurs and the following error message is displayed:
%SYSTEM-F-DEADLOCK, deadlock detected

How to resolve this problem:

Mount the volume specifying a different volume label and use the /OVERRIDE=IDENTIFICATION command qualifier. This will override the volume's label so as not to conflict with the volume set's label.

Undefined Record Format Errors
Many ISO 9660 CD-ROMs are mastered without a specified record format because the ISO 9660 media can be mastered from platforms that do not support the semantics of files containing predefined record formats.

OpenVMS file system utilities (such as TYPE and COPY), language RTLs, and applications that use RMS for record access may report RMS errors, utility errors, and language errors when accessing files whose record format is undefined or appears illegally specified.

How to resolve this problem:

Use the following command syntax at mount time to force all files of type UNDEFINED to the STREAM record format having a maximum record length of 512 bytes:MOUNT/MEDIA=CDROM/UNDEFINED=(STREAM:512) device label

For more information about RMS record formatting, refer to the OpenVMS Record Management Utilities Reference Manual and the OpenVMS Record Management Services Reference Manual .

**Table 15** **ISO 9660 Restrictions**
Media Affected	Description and Resolution
Volume Labels	These can contain from 1 to 32 characters. The first 12 characters are used to produce a unique volume identity. If the label is not unique within the first 12 characters, the volume will not mount and the following error message is displayed: %SYSTEM-F-VOLALRMNT, another volume of the same label already mounted How to resolve this problem: Mount the volume specifying a different volume label and use the /OVERRIDE=IDENTIFICATION qualifier. This will override the volume's label so as not to conflict with the label of an already-mounted volume.
Volume Set Labels	These can be from 1 to 128 characters in length. The first 12 characters are used to produce a unique volume set identity. If the volume set label is not unique within the first 12 characters, the volume will not mount and one of the following error messages will be displayed: %SYSTEM-F-VOLINSET, volume is already part of another volume set %MOUNT-F-DUPRVN, duplicate volume number already mounted How to resolve this problem: Mount the volume specifying a new volume set label with the /BIND=volume-set-name command qualifier.
Volume Label and Volume Set Label Duplication	The first 12 characters of both the volume label and the volume set label are used to produce different lock manager resource names, which are then used to coordinate volume and volume set associations. If both the volume label and the volume set label are the same (within the first 12 characters, including null labels), a lock manager deadlock error occurs and the following error message is displayed: %SYSTEM-F-DEADLOCK, deadlock detected How to resolve this problem: Mount the volume specifying a different volume label and use the /OVERRIDE=IDENTIFICATION command qualifier. This will override the volume's label so as not to conflict with the volume set's label.
Undefined Record Format Errors	Many ISO 9660 CD-ROMs are mastered without a specified record format because the ISO 9660 media can be mastered from platforms that do not support the semantics of files containing predefined record formats. OpenVMS file system utilities (such as TYPE and COPY), language RTLs, and applications that use RMS for record access may report RMS errors, utility errors, and language errors when accessing files whose record format is undefined or appears illegally specified. How to resolve this problem: Use the following command syntax at mount time to force all files of type UNDEFINED to the STREAM record format having a maximum record length of 512 bytes:MOUNT/MEDIA=CDROM/UNDEFINED=(STREAM:512) `device` `label` For more information about RMS record formatting, refer to the OpenVMS Record Management Utilities Reference Manual and the OpenVMS Record Management Services Reference Manual .

Expanding Volumes Dynamically

Mounting Tape Volume Sets

device-name	Specifies the physical device name or logical name of the device on which the ISO 9660 volume is to be mounted.
volume-label	Specifies the SVD volume label obtained from the author's label on the CD-ROM.
escape-sequence	Specifies the escape sequence obtained from the author's label on the CD-ROM.