After adding a vdisk to an ESXi linux guest you will assert that you can't find a new device in the running VM. You have to force a SCSI rescan.
grep mtpspi /sys/class/scsi_host/host?/proc_name
echo "- - -" > /sys/class/scsi_host/<host>/scan
and insert the host found in point two for <host>
cat /proc/scsi/scsi
should now show the new added device