1 migrateexts   -source
2 source_mdisk_id
2 source_mdisk_name
3  -target
4 target_mdisk_id
4 target_mdisk_name
5  -exts number_of_extents
6?  -threads number_of_threads
7?  -copy id
8  -vdisk
9 vdisk_id
9 vdisk_name