Your operators should understand the need for enough work volumes to satisfy requests for temporary data sets at peak loads. A shortage of work volumes can cause the system to request additional scratch volumes so operators need to balance work volumes across channel paths to increase system efficiency.

Operators should not use the MOUNT command for devices managed by JES3. See z/OS JES3 Commands. They also should not mount a blank tape volume because the system scans the entire volume for a tape label and this scanning wastes time. If an unlabeled tape is needed, the operator can write a tapemark to avoid unnecessary scanning. After the operator mounts the tape volume and readies the drive, the system reads the volume label. If an incorrect volume is mounted, the system unloads the incorrect volume and repeats the mounting message.

Occasionally operators might receive two mount messages for the same volume, one starting with IEF and the other with IEC. They should treat the two messages as though they were one. The second is a reminder.

To refer to I/O devices in MVS™ commands, operators can use the unique device number assigned to each device (devnum).

In MVS commands, operators should not specify the symbolic names that programmers use in DD statements to group several devices for allocation to the job.

The IBM® 3495 Tape Library Dataserver performs some operator actions such as mounts, demounts, and swaps. Operators might notice fewer messages associated with these actions. These messages are no longer sent to the console, but rather to the hardcopy log, where they are available for tracing and diagnosis.