Hello,    That is very old firmware.  To be clear this is not a Dell supported method to upgrade drive capacity.  You accept all risks to your data if there should be additional drives failed during so many rebuilds.     Re: Spare.  Yes. that has to be the first one replaced.  Otherwise it will simply rebuild on to the existing 600GB drive.   When you replace the spare, then pull the first data drive, it will rebuild onto the 1.2TB drive but only use 1/2.  That pattern will repeat itself until all the drives are replaced.    Regards,  Don  #iworkfordell 
Hi everyone, I want to expand my Dell EqualLogic PS6100. I am running it with raid 6, and 24 drives and each of them has 600GB and 1 hot spare. I just bought two 1.2TB drives, I want to ask that after I replace them 1 by 1, what will I need to do next? or can someone show me the whole process of this replacement? Thank you for helping and I really appreciate that. 
Expand storgage of Dell EqualLogic PS6100