Shut down any client applications, unmount LUNs, etc ...
Log on to a mgt LIF on the second node.
system node halt -node node1 -reason 'disaster coming' -inhibit-takeover true
system node halt -node node2 -reason 'disaster coming'
Turn off controllers, disk shelves and switches.
Turn on switches, then shelves, then controllers.
If autoboot isn't set then 'boot_ontap' from the sp or console.
See also 'System Administration Guide' portion of the documentation.
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff
Senior Consultant, K&H Research http://www.khresear.ch/
Senior Instructor, Unitek Education http://www.unitek.com/training/netapp/