VMware ESX provides native support for iSCSI targets. iSCSI is a popular storage option for ESX hosts.

As stated on VMware.com:

VMware Ready designates VMware's highest level of endorsement for products created by our established partners. VMware Technology Alliance Partner members can develop their products to meet VMware standards and submit them for test and review. The VMware Ready certification tests are specifically designed for each category to ensure customer confidence.

ESX provides only two ways to access network based storage, either iSCSI or NFS shares. iSCSI generally provides a higher performance, more flexible storage option and is almost always the preferred option.

If you contact VMware support for assistance with an unsupported storage solution, their ability to help you will be limited.