ok stan;i have posted the result of the mt command,well i will posted them 
again for you :

mt -f /dev/rmt1.1 status
mt -f /dev/rmt21 status

I have tested the devices with the mt command; the only difference between 
themes is: 
/dev/rmt1.1 
lun_id 0x1000000000000 Logical Unit Number ID False 
/dev/rmt2.1 
lun_id 0x2000000000000 Logical Unit Number ID False 

with the same : 
FC node 
node_name 0x100000e00203649f FC Node Name False 

and SCSI ID !!! 
scsi_id 0x10200 SCSI ID False 

Is the fact that they have the same SCSI ID is correct ?! 
how to get persistent binding set in the OS for tape devices ?.

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