While most system vendors offer hardware that is compatible with VMware vSphere, only a subset of the hardware in the VMware Compatibility Guide is applicable for use for VSAN. It is important to make sure that all applicable hardware exists in both guides. The storage-specific components like hard-disk controllers and disks must meet the more-exhaustive performance and reliability requirements for VSAN.
You should have some idea of your hardware requirements. This includes an estimate of your needs for system memory (RAM), along with processor power, networking needs, and storage requirements in terms of capacity and performance.
Go to your web browser and navigate to both the regular VMware vSphere Compatibility Guide at http://www.vmware.com/resources/compatibility/search.php and the VMware VSAN Compatibility Guide at http://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan.
The first link will take you to the standard VMware Compatibility Guide, and the second will take you to the VSAN sub-guide. By default, you will land on the system/server page, to help you select a server platform.