Alshawwa,  The process is simply to run the update with the Customized ISO. I assume the hypervisor resides on the SD cards, so if that is the case then select them for the update. The 7GB is ample room for the hypervisor and upgrade. The ISO is just showing the hard drives, as well as the 2 redundant SD cards (7GB's).   Let me know how it goes.
I got a couple of R730 Brand new that came preinstalled with ESXI 5.1 u2 ,on dual flash cards and the size of each one of them is 7GB what is the procedure to upgrade the esxi from 5.1 to 5.5 on PowerEdge R730 using the dell customized iso"  , and will 7GB be enough for the upgrade process?  thanks   * booting up from the iso shows 300GB datasore and two 7GB datastores * 
Esxi 5.1 updrade to 5.5u2 PowerEdge R730