This example uses Instance = QUSROND and ASP = 01.
To view the status of the UDFS:
DSPMFSINF OBJ('/dev/qasp01/ondemand_QUSROND_primary_01.udfs')
When it is mounted you have More... at the bottom showing an additional screen of information and when you page down you see:
Path of mounted file system . : /DEV/QASP01/ONDEMAND_QUSROND_PRIMARY_01.UDFS
Path mounted over . . . . . . : /QIBM/USERDATA/ONDEMAND/QUSROND/ASMASP01/PRIMARY
(My example is an instance called QUSROND)
If it is not mounted, the second page of information would not be available.
To unmount the UDFS:
CALL QRDARS/QRLCASMUFS PARM('QUSROND')
OnDemand mounts the file system automatically when it is needed, but if you wanted to mount it manually - which is useful for looking for objects before OnDemand is active you can use this mount command:
MOUNT TYPE(*UDFS)
MFS('/dev/qasp01/ondemand_qusrond_primary_01.udfs')
MNTOVRDIR('/qibm/userdata/ondemand/QUSROND/ASMASP01/PRIMARY')