I have similar issue. and I am planning to make above stated changes. However I am bit new in this Fabric world so just willing to have few checks.
Q 1: I can straight away perform hareboot on my 5840 series (6.4.0c) - I read some thread stating, execute it on active CP. if that is the case, how can we execute hareboot on active cp.
Q2: As I can see the command is hareboot, is there any remote possiblity that it may interrupt FC traffic even for a milisecond on my 5480 embedded switch gear having FOS 6.4.0c
Your answer is highly appreciable.
In response to your queries:
Q1: Yes, you can. 5840 has only one CP (so it is always active). In order to execute it, just run commnad 'hareboot'
Q2: Theoretically, it does not affect FC traffic, but in this world of ours nothing is 100% secure and the remote possibility of a failure always exists.
On the other hand, FOS 6.4.0c is a little bit old and I recommend you to upgrade to the latest release supported by your switch.