The PERC H700 (with the latest firmware) can support drives larger even than 2TB, so 1TB drives are just fine.   The maximum limit for the size of an array on the H700 is well beyond the capacity of any of Dell's current servers. You can increase the size of the RAID array, while online (called Online Capacity Expansion), but only by ADDING disks to your RAID 5.  You cannot replace the disks individually with larger ones to make the array larger - you would need to backup/replace/create/restore.
Hi I have number of R810 servers that have PERC H700 RAID controller on it. currently controller have 6x300GB SAS (2.5" 10K) HDD on it. is it possible to replace all the 6 HDDs with 900GB SAS (2.5" 10K) HDD from Dell (link below)?   is PERC H700 capable of supporting 1TB HDD? What is the maximum TB capacity for PERC H700 (RAID 5)? also, is it possible to increase the RAID volume without shutting the system down and rebuilding the RAID?   Thanks for your response     
PERC H700 HDD compatibility list