Which protocol does NOT have support from FlexCache software?

FlexCache is a NetApp feature designed to enhance performance by creating caching solutions for both NFS and SMB protocols. It allows clients to access cached data faster without having to constantly retrieve it from the primary storage location.

In this context, the protocol that does not have support from FlexCache is NFSv4. While FlexCache supports NFSv3, which is widely utilized for data sharing in many environments, as well as SMB (Server Message Block), NFSv4 was designed with different capabilities and features that do not align with how FlexCache operates. Specifically, NFSv4 includes stateful operations and integrated security features that complicate its interaction with a caching layer, making it less compatible with FlexCache compared to its predecessors. Therefore, the reliance on NFSv4's features renders it unsupported by FlexCache.

The other protocols mentioned, such as NFSv3 and SMB, are aligned with the functionality that FlexCache provides, allowing for efficient caching of file data which improves read response times and overall system performance.