vim.fault.FileTooLarge error when creating or migrating large VMDKs on NetApp NFS - VMware vSphere ESXi

Products

• VMware vSphere ESXi

Issue/Introduction

• Migrating a Virtual Machine (VM) to an NFS datastore fails with the error: N3Vim5Fault12FileTooLarge9ExceptionE(Fault cause: vim.fault.FileTooLarge).
• Creating or expanding a virtual machine disk (.vmdk) beyond 15.8 TB (16 TiB) fails instantly.
• The vSphere Client UI displays: Error creating disk: The destination file system does not support large files.
• Host hostd.log contains: sub=Libs DiskLibIsCapacitySupported: Unsupported disk capacity #### bytes. Allowed disk capacity 17383785916071 bytes.

Symptoms

• Failures occur when attempting to provision disks larger than 16 TiB (e.g., 19 TB or 25 TB disks) on NetApp ONTAP or Azure NetApp Files (ANF) volumes.
• The destination storage supports large files, but ESXi continues to enforce a legacy 16 TiB limit despite storage-side expansions.

Environment

• VMware vSphere ESXi 7.x, 8.x
• NetApp ONTAP Storage (NFSv3 or NFSv4.1)
• Azure NetApp Files (ANF)

Cause

The ESXi host DiskLib enforces a cached 16 TiB file size limit established during the initial NFS mount. When an NFS datastore is mounted, ESXi queries the storage controller to determine maximum file system boundaries. If the storage volume or ONTAP version at the time of mounting did not support files larger than 16 TiB, ESXi caches this limit in active memory. The hypervisor does not dynamically refresh these boundaries; it continues to enforce the legacy restriction until the mount is re-initialized.

Resolution

To allow provisioning of disks larger than 16 TiB, you must force a client handshake refresh by remounting the datastore across the cluster during a maintenance window.

Step 1: Verify Storage Support

Ensure the backend storage is configured for "Large File Support":

• For NetApp ONTAP: Confirm with your storage administrator that the specific volume supports files larger than 16 TiB. See NetApp ONTAP Large File Support Documentation.
• For Azure NetApp Files: Review the Microsoft ANF Storage Limits FAQ to ensure the volume tier supports up to 64 TiB single-file allocations.

Step 2: Refresh ESXi Host Cache via Remount

1. In the vSphere Client, navigate to the Storage view.
2. Identify all virtual machines on the affected NFS datastore.
3. Migrate these VMs to another datastore using Storage vMotion or power them off.
4. Right-click the datastore and select Unmount Datastore.
5. Select all ESXi hosts in the cluster and confirm the unmount.
6. Once unmounted, right-click the Cluster/Datacenter, select Storage > New Datastore.
7. Mount the datastore again using the same Export Path and Server IP.

Step 3: Validation

1. Select the remounted datastore and check Summary > General.
2. Verify the Maximum File Size now reflects the updated value (e.g., 64 TB).
3. Re-attempt the VM migration or disk expansion.

Fixed in release vSphere ESXi 7.0 and higher. See Download Broadcom Products and Software to download this release.

Additional Information

• Related KB: For specific Azure NetApp Files (ANF) context, see KB 445675.
• For automated updates on fix status, subscribe to this article. See How to subscribe to Knowledge Management (KM) articles.
• To speak with a customer representative or a Support Engineer see Contact Support. Scroll to the bottom of the page and click on your respective region.