The H710p would not even try to use the 300 to rebuild the 1.8TB drive failure, as the drive isn't going to be seen as a valid Hot Spare for that Virtual Disk. A 300GB global Hot Spare would be able to rebuild to any 300GB or smaller drive. If the Global Hot Spare is a 1.8TB it would rebuild to any of those Virtual Disks. 
I want to add disk storage to an existing Dell PowerEdge T620 . It currently has 7 300GB SAS 2.5" hot swap drives, two virtual drives (RAID1 300GB and RAID5 1116GB). There are 16 bays.  Browsing the Dell store for server upgrade parts I am surprised to see only two form factors for 2.5" 10K rpm SAS drives. Only 300GB or 900GB. Nothing with higher speeds or higher capacity!? And I'm not even sure one of the search results is really 2.5" since the website product description does not indicate the size at all. 300GB  Manufacturer Part# : 15NM6 | Dell Part# : 342-2016 (accessories.dell.com/.../productdetail.aspx 900GB Manufacturer Part# : TPMWF | Dell Part# : 342-4143 ([URL] The 900GB is described as a Hybrid drive. What is a hybrid drive? Isn't SAS, SAS? There are several results which all seem to be variations on the 300GB SAS6 10K 2.5" drive. Are they all the same product? Why the different part numbers?
Need Help Selecting Correct Upgrade SAS 2.5" HDD for PowerEdge T620