I'm setting up a new Windows Server 2012 R2 server. The server has 3 x 600 GB 15K SAS hard drives in a RAID-5 array plus one hot spare. My plan is to setup a Hyper-V host and then create two or three VMs (depending on whether the customer wants to pay to license the 3rd/4th instance). The customer environment is relatively small. Initially, there will be 6 users on the network with a 7th user connecting remotely. There may be 10 or 12 users max within two years. The workloads are Hyper-V by itself on the host O/S, Active Directory (guest O/S), Remote Desktop Services (guest O/S) and possibly applications/data in a 3rd guest O/S. If we stick with only 2 VMs, the applications and data would have to go on one of the other two guests. In my research of best practices, several people recommend putting the host O/S on a RAID-1 array and then putting everything else on a separate array, such as a RAID-5 array. I'm wondering if this type of setup is really necessary in a smaller environment (i.e. 10 users) and if I would even notice a performance difference if I just did everything on a single RAID-5 array. My server already has the RAID-5 array as well as Windows Server 2012 R2 Standard installed, and right now I only have a total of 4 hard drives. I'd like to proceed with my original plan, but wanted to get some advice from the "Experts" on whether or not this would be a big mistake. Thanks.