Although enabling iSCSI Target Server to provide block storage for your environment requires no other hardware than your existing Ethernet network and a server running Windows Server 2012, there are some additional considerations you need to be aware of:
You cannot host iSCSI virtual disks on physical disks that have been added to a storage pool on the server. In other words, iSCSI Target Server in Windows Server 2012 is not compatible with the new Storage Spaces feature of this platform.
iSCSI virtual disks can be backed only by VHD files and not the newer VHDX files that are used by default by Hyper-V in Windows Server 2012.
You can create new iSCSI virtual disks only on NTFS volumes, not on volumes formatted using the new Resilient File System (ReFS) in Windows Server 2012.
The above tip was excerpted from Mitch Tulloch's book Training Guide: Installing and Configuring Windows Server 2012 from Microsoft Press.
Mitch is a nine-time recipient of the Microsoft Most Valuable Professional (MVP) award and a widely recognized expert on Windows administration, deployment and virtualization. For more information see http://www.mtit.com.