-.RB -m , --mdt-index
-Causes the file metadata (inode) to be migrated to the MDT with index
-.IR mdt_idx .
-This is useful if new MDTs have been added to a filesystem and existing
-user or project directories should be migrated off old MDTs to balance
-the space usage and future metadata workload.
+.BR -m , --mdt-index=\fIstart_mdt_index\fR
+Directory will be migrated to MDTs starting with
+.I start_mdt_index
+, or specific MDTs if multiple MDTs are specified in a comma-seperated list.
+This is useful if new MDTs have been added to a filesystem and existing user or
+project directories should be migrated off old MDTs to balance the space usage
+and future metadata workload.
+.TP
+.BR -c , --mdt-count=\fICOUNT\fR
+Directory will be migrated to
+.I COUNT
+MDTs.
+.TP
+.BR -H , --mdt-hash=\fIHASH_TYPE\fR
+Use
+.I HASH_TYPE
+for the new layout.
+.RS 1.2i
+.TP
+.B all_char (type 1)
+Sum of ASCII characters modulo number of MDTs. This
+provides weak hashing of the filename, and is suitable
+for only testing or when the input is known to have
+perfectly uniform distribution (e.g. sequential numbers).
+.TP
+.B fnv_1a_64 (type 2)
+Fowler-Noll-Vo (FNV-1a) hash algorithm. This provides
+reasonably uniform, but not cryptographically strong,
+hashing of the filename. (default)
+.TP
+.B crush (type 3)
+CRUSH hash algorithm. This is a consistent hash
+algorithm, so minimum sub files need to relocate
+during directory restripe.
+.RE