I'm managing a HP DL360 G5 machine. It has a SAS controller(P400i) with two ports. Port 1 is attached to 4 drive bays and Port 2 has 2 bays. The machine currently has 3 drives connected to Port 1 with RAID 5 configuration. I'm trying to max out the bays by adding 1 disk in port 1 and 2 in port 2. Can I group those three disks(1 disk-port, 2 disks-port 2) in a RAID 5 configuration?
Most likely, yes. You'll need to provide more information (like what controller it has installed) to get a 100% sure answer.
Yes, you've probably got a HP P400/I in there and you can create arrays that span physical ports as easily as you can disks on the same port. Some cards have additionally-licenced extra features (R6/R10 etc.) but for basic arrays you'll be just fine, ask again on this thread if you need hands-on help ok.