The described symptoms—a successfully mounted and visible NFS datastore where write operations fail—are a classic indicator of a permissions issue on the NFS server. The NFS protocol allows a share to be exported with read-only permissions. In this state, an ESXi host can successfully mount the datastore and read its metadata (making it visible in the vSphere Client), but any attempt to write data, such as creating a virtual machine or a file, will be denied by the NFS server. Therefore, the most logical next step is to verify the export permissions on the NFS server to ensure they are configured for read-write access for the specific ESXi hosts.

A. Hardware compatibility issues typically manifest as an inability to mount the datastore, instability, or poor performance, not a specific failure of only write operations.

B. Rebooting a host is a disruptive, last-resort action. It is not the appropriate next step for troubleshooting a likely permissions issue, which can be diagnosed non-intrusively.

D. An MTU size mismatch would likely cause packet fragmentation and loss, leading to performance degradation or a complete failure to mount the datastore, rather than a clean read-only state.

1. VMware vSphere 8.0 Documentation, "vSphere Storage," Chapter: "Working with Network File System Datastores," Section: "NFS Storage Guidelines and Requirements."

The documentation states, "Ensure that the NFS volume is exported from the NFS server with read/write permission for the ESXi hosts... If you export the volume with the read-only permission, you cannot create virtual machines on the datastore." This directly supports checking permissions as the cause for being unable to write.

2. VMware Knowledge Base Article 1003967, "Troubleshooting the failed creation of a virtual machine on an NFS datastore."

Under the "Cause" section, this article lists "The NFS volume is mounted as read-only" as a primary reason for this issue. The resolution steps guide the administrator to check the NFS server's export configuration (e.g., /etc/exports on a Linux server) to ensure the rw (read-write) flag is set for the ESXi hosts.

3. VMware Cloud Foundation 5.1 Documentation, "Administering a VMware Cloud Foundation Workload Domain," Section: "Supplemental Storage for Workload Domains."

This guide details the process of adding supplemental storage, including NFS. It notes that for operational procedures and troubleshooting of the underlying storage technology, administrators should refer to the standard vSphere documentation. This confirms that fundamental vSphere troubleshooting principles, such as checking NFS permissions, are the correct procedure within a VCF context.