Loading, unloading, and varying on optical devices

Loading a CD-ROM, DVD, or RDX media into a drive, inserting a USB flash drive, or varying on an optical device 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, and 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 optical media is loaded into a varied-on device.
Note: Optical media can also 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 the device description for an optical device with media in it.

It can take an extended amount of time before an optical device is ready to use after media is loaded or it is varied on. For CD-ROM or DVD devices, it can take up to 1 minute before the device is ready to use. For RDX and USB flash drives, it can take up to 10 seconds before the device is ready to use.

When the user successfully loads optical media into a drive, the system sends the following message to the QSYSOPR message queue:

Volume VOLID01 added to optical device.

When optical media 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 optical media.

You can also use the Display Optical (DSPOPT) command to display optical volume information.

Occasionally media might fail to load successfully into the drive. The following list shows some of the possible causes for an unsuccessful load:

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 might or might 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 might 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.