Reasons a volume is not placed on the primary list

A volume is not placed on the primary list if it does not meet all of the criteria listed in Table 1, or for one of the following reasons:

The volume is rejected. See Possible reasons for volume selection failure for more information.
The VTOC index is broken or disabled, resulting in SMS not being updated with space statistics from the Common VTOC Access Facility (CVAF). This can also happen if OEM products bypass CVAF, the component that notifies SMS of space changes. SMS not being updated with space statistics can also result in a volume being overused.
The volume was placed on the tertiary list because the number of volumes in the storage group was less than the number of requested volumes.
For example, this happens when a tape request of five volumes causes a tape mount management buffer storage group containing only two volumes to be marked tertiary, while an overflow storage group or a quiesced storage group containing the requested five volumes is marked secondary. The overflow volumes and quiesced volumes on the secondary list are preferred over the tape mount management volumes on the tertiary list. SMS will attempt to allocate space using the overflow volumes first, then the quiesced volumes, and lastly the tape mount management buffer volumes.
The controller was IMLed while online to MVS. This can result in the MVS device control blocks not reflecting the current state of the volume. The device or devices should be varied offline and back online to update the MVS control block status.
RAID devices are eliminated from the primary list when STANDARD is specified. Use NOPREF, the AVAILABILITY default, to allow both SIMPLEX and RAID devices to be placed on the primary list.

For more information to help you determine why a particular volume is selected or not selected, see Table 1.