Well if it's killing the network then just remove the network cable.
What size is the array? Large arrays can take tens of hours to initialise.
Also I can't say I recommend removing the drive. If you've got data in the array and you are just expanding you are putting it at risk. If it's a brand new system I suppose the worst thing that could happen would be that you'd get the system in a tizzy and you may have to do a factory reset.