Loading and unloading CD-ROM and DVD media

 

Loading a CD-ROM or DVD media into a drive causes the system to read the media to retrieve the volume identifier. The system stores this volume identifier in an optical index database file to expedite future access to the media. After the volume identifier is in the optical index, you can access the media through save and restore options, as well as the application programming interfaces. Unloading the media from the drive removes the volume identifier from the optical index. The system adds the volume identifier to the optical index database in one of two ways:

• When the CD-ROM or DVD is loaded into a varied-on device, a CD-ROM or DVD can be loaded into a varied-off device. However, the optical index is not updated until you vary on the device description.

• When the user varies on a CD-ROM or DVD device description with media in it.

Additional processing could take several seconds after the tray slides in before the CD-ROM or DVD is usable. This is true for varying on as well.

Even if the vary-on operations completed successfully, the CD-ROM or DVD is not usable until the system reads and stores the media information in the optical index. This may take several seconds after the vary-on operation is completed.

When the user successfully loads a CD-ROM or DVD into a drive, the system sends the following message to the QSYSOPR message queue:

Volume VOLID01 added to optical device.

When a CD-ROM or DVD is successfully removed from a drive, the system sends the following message to the QSYSOPR message queue:

Volume VOLID01 removed from optical device.

You can use the Work with Optical Volumes (WRKOPTVOL) command to verify the successful adding or removing of the CD-ROM or DVD.

You can also use the Display Optical (DSPOPT) command to display optical volume information. Occasionally media may fail to load successfully into the drive. Some of the possible causes for an unsuccessful load are listed below:

• Media or drive error occurred.

• The media format is not supported (digital audio CD-ROM).

• The system encountered a duplicate volume identifier.

Depending on the error, the tray may or may not eject if a CD-ROM or DVD fails to load. A failure to load the CD-ROM or DVD might not be obvious. Your first indication may be that you received one of the following messages when trying to access the CD-ROM:

Optical volume format not recognized. 
Optical volume not found.

If an error does occur when loading media or varying on the drive, the system signals an error message to the QSYSOPR message queue. This message describes the reason for the failure.

The processing for the load, unload, and vary-on operations runs in job QJOBSCD. If errors occur during these operations, view the job log of QJOBSCD to see the detailed messages.

 

Parent topic:

Using optical devices