Hello briandohth,   When upgrading drives you would not be able to replace one at a time. You would to replace every drives at once and start over with a new raid array.   I would recommend to contact Sales for compatible drives with Equallogic firmware. I have been looking for a compatibility matrix but I have not found one yet.
We are currently using the Dell EqualLogic PS6100 with 24 drives ( Raid 6; 600GB each) > We are looking forward to upgrading our system with double up or triple up the size of the storage. There are 2 big concerns we are facing right now.  First, I would like to know the price of each upgrade ( double up and triple up )  Second, I would like to know the best way to clone all the data from the existing drives to the new one if we upgrade without interrupting the sever or anything else related to this server. For example, can i plug in the new disk right after i remove the old one ( one by one )? [IMAGE]
Dell EqualLogic PS6100