I have to migrate a volume from filerA to filerB , instead of using snapmirror, i will give ndmpcopy a chance.
Like snapmirror it is a block level transfer(lot faster than rsync). The benefit for this would be the single file/directory that we are able to move. snapmirror transfer entire volume while ndmpcopy, we can copy a single directory within a volume, and yet still using block level.

Below is just the example output i have for references:
I am copying from a FAS3170 to FAS960
Directory size: 1.5TB
~45MBps!!!!
Time taken: 9 hours 15 minute
Ndmpcopy: filerA: Log: DUMP: dumping (Pass V) [ACLs]
Ndmpcopy: filerA: Log: DUMP: 1563223738 KB
Ndmpcopy: filerB: Log: RESTORE: RESTORE IS DONE
Ndmpcopy: filerB: Log: RESTORE: The destination path is /vol/vol_restore/re store/
Ndmpcopy: filerB: Notify: restore successful
Ndmpcopy: filerA: Log: DUMP: DUMP IS DONE
Ndmpcopy: filerA: Log: DUMP: Deleting “/vol/fc_loan/../snapshot_for_ backup.195” snapshot.
Ndmpcopy: filerA: Notify: dump successful
Ndmpcopy: Transfer successful [ 9 hours 15 minutes 47 seconds ]
Ndmpcopy: Done