VMware Getting Started - Storage Enclosure Guidance
There are many options for storage enclosures, including chassis with redundant power supplies, redundant cabling in both 3.5" and 2.5" form factors.
After you have chosen which of the above methods of connecting JBOD (just a bunch of disks) to VMware, then you are ready to install and configure SoftNAS. If you are just giving SoftNAS a try on a smaller-scale basis, then almost any VMware-compatible disk storage will suffice as a starting point. Just remember, you don't need to spend a lot to get high-performance, high-quality NAS capabilities with SoftNAS, as there is enormous flexibility and choice available due to the broad compatibility provided by VMware and Linux.
Please review RAID Considerations for additional information on available and recommended data disk configurations.