Recommended "disk" encryption software for Server 2012 w/ RAID5?

Just received a PowerEdge T330 server, with Win2012 Essentials & 4 disk RAID5

So, within Win2012 o/s, we have partitions:
C:\  250 GB (System)
G:\  1.2 TB (Data)

We are needing to apply a subsequent software layer of encryption of the Windows partitions, due to nature of our business...

We have 2 options available:
1) a license of Symantec PGP
2)  using the native Win BitLocker

Any recommendations for software layer encryption of Win2012, particularly with RAID5... to not impact function or performance?