1. You should NOT turn it off to add or replace hot-swappable drives. Leave it on. 2. Yes, use OpenManage ... choose Reconfigure from the dropdown menu of Available Tasks for the RAID 1. 3. Yes, the drive can be larger, but not smaller. All space larger than other member disks will be wasted space. So, you will go from a 1TB RAID 1 to a 4TB RAID 5. Half of all your 2TB disks will be wasted. Another thing you should know is that if Windows is not ALREADY installed with UEFI enabled (as opposed to BIOS), then you cannot use more than 2TB. Windows cannot use a disk larger than 2TB unless it is GPT, and Windows cannot boot a GPT disk unless installed on UEFI-enabled system. Conversion to GPT is data-destructive, so it cannot be changed without reinstalling. My advice would be to configure your 4x2TB disks into a 4TB RAID 6 - RAID 6 is a better use of a "hot-spare" than a standby hot-spare. RAID 10 would also be acceptable.
Hello, We have one Dell PowerEdge T320 with the following Perc  Right now the server has two 1TB drives on a RAID 1 single virtual drive. I want to add 4 more drives (2TB each) and create a RAID 5 with 3 drives and leave one as a hot spare. So my questions are: 1. Do I need to turn off the server in order to add the new drives? - the server has the front bay access area to the Perc connections, They are SATA drives.  2.What would be the appropriate steps to configure the RAID. Is this something I can do using Dell Open Manage? 3. Do you know if the 2TB drive I will use as a hot spare will also work for the 1TB RAID 1 drives? Thanks in advance.  
Do I need to shutdown PowerEdge T320 to add more drives?