Upgrading hard disks in RAID 1 configuration on PowerEdge T110 ii

Afternoon everyone,

We're considering upgrading the disks on our PowerEdge T110 ii which uses the PERC S100 SATA RAID controller. The server is also running SBS 2011 and Exchange Server 2010 which will soon be upgraded to Server 2016 Essentials and most likely Office 365 instead of Exchange Server - but that's another project.

Currently we have two 1TB disks in RAID 1 which are approaching full, so the plan is upgrade to two 4TB disks to give us some extra room. I'm just wondering if some one could talk me through the process of doing this as it seems to depend on the specific RAID controller you have and I have not done this involving RAID before? 

My plan was to power off the server, remove one of the old disks and install one of the new large disks in it's place, then use the software to rebuild onto the larger disk. Once complete I'd then repeat the process with the second larger disk and the one remaining old small disk. Once that is complete I'd have my two new disks running and I'd just need to extend the partition to allow for accessing the extra space - however having done some reading I'm not sure it would be that simple?

Thanks for your time,

Jon.