Hello Jim,
I am glad to hear that my last email helped you. Thank you very much for sharing your results with us :-).
I would say it is quite ambitious to have the same autochanger dealing with different media types, even having specific devices for each medya type. I hope this do not cause confusion in the future :-).
Regarding the strange behavior you reported due to using together Maximum Concurrent Jobs, UseVolumeOnce, and Maximum Volume Jobs, please find some explanation I collected from the Main Manual:
* about UseVolumeOnce:
"This directive will most likely be phased out (deprecated), so you are recommended to use Maximum Volume Jobs = 1 instead."
* about MaximumVolumeJobs:
"If you are running multiple simultaneous jobs, this directive may not work correctly because when a
drive is reserved for a job, this directive is not taken into account, so multiple jobs may try to start
writing to the Volume. At some point, when the Media record is updated, multiple simultaneous jobs
may fail since the Volume can no longer be written."
I was able to see this behavior a few times. It happens very often if too many concurrent jobs are run.
The first thing a job does is to reserve a volume. Suppose you have a single Storage resource (a disk device, for example), allowed to run 5 concurrent jobs.
Also, that MaximumVolumeJobs is set to 4, for example.
The 5 jobs started simultaneously will reserve the same device/volume, but the 4th job will mark the volume as "Used" and the 5th job will hang because it will not go for another volume.