VMware ESXi 5 is not able to handle multi-lun devices by default, so many SCSI autoloaders are not supported as-is (as HP StorageWorks LTOs), showing only the tape drive or media changer but not both:

To have it work in ESXi it’s enough to:

  1. Get a multi-LUN aware SCSI controller. Notice that many RAID controllers can’t handle multi-lun targets. I’ve used an Adaptec 29320.
  2. Run the following on ESXi: esxcli storage nmp satp rule add --satp VMWSATPLOCAL --driver="aic79xx" --description="Specific rule for Adaptec Card"
  3. Issue a bus rescan

After that you should be able to see both the tape and the autoloader, as show in the following image: