Question about DE2 Addition with ONLINE I/O service

Hello.

I would like to know that how to set the offline IOM module. (e.g. cli)

1. Question background.

Cu has ZS3-2 cluster (A/A) with 4 trays in two loops. each loop has two trays.
Cu wants to add the new each 2 DEs on exited each loop without Service Downtime. (total 4 DEs trays additional)

2. Question

To do this, I think that there be IOM Module offline/online when the SAS cabling change/add one by one.
To keep the service I/O, included in ZFS internal disk I/O).

If both IOMs on same tray have busy (checked by LED lamp blinking.), the SAS expander cable remove/install task could be dangerous without one IOM offline/online task).