NetApp AFF A200 System Documentation page 1574

If your IOM6 stack connectivity is...
Multipath HA or multipath, or single-path HA with
controller connectivity to the logical last shelf
(including stretch MetroCluster configurations)
Then...
a. Disconnect the controller-to-stack cable from
the last IOM6 shelf IOM A circle port to the
controller or bridge.
Make note of the controller port.
Put the cable aside. It is no longer needed.
Otherwise; go to substep e.
b. Cable the shelf-to-shelf connection between the
last IOM6 shelf IOM A circle port (from substep
a) to the new IOM12 shelf IOM A port 1.
Use a SAS copper QSFP-to-Mini-SAS HD
cable.
c. If you are hot-adding another IOM12 shelf,
cable the shelf-to-shelf connection between the
IOM12 shelf IOM A port 3, of the shelf you just
cabled, and the next IOM12 shelf IOM A port 1.
Use a SAS copper Mini-SAS HD-to-Mini-SAS
HD cable.
Otherwise, go to the next substep.
d. Reestablish the controller-to-stack connection
by cabling the same port on the controller or
bridge (in substep a) to the new last IOM12
shelf IOM A port 3.
Use a SAS copper QSFP-to-Mini-SAS HD cable
or Mini-SAS HD-to-Mini-SAS HD cable, as
appropriate for the port type on the controller.
e. Repeat substeps a through d for IOM B.
Otherwise, go to step 4.
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