Adding an existing RDM to a virtual machine fails with the error: Error creating disk: The destination file system does not support large files

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Adding existing RDMs to a virtual machine fails.
• You see the error:
  
  Error creating disk: The destination file system does not support large files
  
  
• Adding an RDM fails even though the size of the RDM fulfills the condition of block size of the datastore (for example, you cannot add an RDM of 400 GB on a 1 MB block size VMFS3 datastore).
• This issue occurs if there are a set of RDMs that were presented to a virtual machine and a filesystem was set up by concatenating them using the filesystem LVM.
• This issue may occur when a physical server is virtualized and the existing physical LUNs are being added as RDMs to the virtual machine. The caveat is that these physical LUNs have been concatenated inside the operating system.

Environment

VMware ESXi 3.5.x Embedded
VMware ESX Server 3.5.x
VMware ESXi 3.5.x Installable
VMware ESX Server 3.0.x
VMware ESXi 4.1.x Installable
VMware ESX 4.0.x
VMware vSphere ESXi 5.1
VMware vSphere ESXi 5.0
VMware ESXi 4.0.x Installable
VMware ESXi 4.1.x Embedded
VMware vSphere ESXi 5.5
VMware ESX 4.1.x
VMware ESXi 4.0.x Embedded

Resolution

Scenario:

• You have a physical Windows 2003 Server with 5 LUNS of 100 GB each presented to it for storage.
• The first LUN (100 GB) has the operating system installed on it and the other 4 LUNs (100 GB each) have data.
• Inside the operating system, you can concatenate all the data LUNs and make a single volume using Disk Management or third-party software. This makes the data volume 400 GB.

If you decide to virtualize this server and keep the existing data volume and attach that as an RDM, you create a new virtual machine or convert the existing one with only the operating system LUN attached. This gives you a Windows virtual machine on the ESXi/ESX infrastructure.

The next step is to add the 4 LUNs of 100 GB each to the virtual machine. At this stage, when you add the LUNs as RDMs (physical or virtual), you can create a Link (Mapping VMDK) for these LUNs on a 1 MB block size datastore because it is a supported file size. For more information, see Block size limitations of a VMFS datastore (1003565).

However, this procedure fails with the error:

Error creating disk: The destination file system does not support large files

This procedure fails when the first RDM is attached and read by the ESXi/ESX host if the filesystem is not supported by a 1 MB block size datastore (for example, a 400 GB file size is not supported by a 1 MB block size VMFS3 datastore).

To add RDMs with larger spanned volumes, you must determine the size of the spanned partition and choose a datastore with a larger block size to support the VMDK (for example, 2 MB for a 500 GB VMDK, or 4 MB for a 1 TB VMDK).

Note: If you want to add an RDM to the second node in an MSCS cluster with a LUN that was removed and then presented again to the ESXi/ESX host and mounted as an RDM on the virtual machine, be sure to check the /var/log/vmkernel log for matching LUN UID/serial number for that LUN.

Additional Information

The scenario and symptoms above describe a specific situation.

If the RDM is larger than 2 TB - 512 bytes in size, the error may still appear when using a VMFS3 datastore. To work around this issue, create a large RDM to a VMFS5 datastore or upgrade the existing VMFS3 datastore to VMFS5. For more information, see Frequently Asked Questions on VMware vSphere 5.x for VMFS-5 (2003813).

Warning: VMFS5 is only supported on ESXi 5.x hosts. All other hosts will lose access to a datastore when upgraded to VMFS5.

Summary of support for RDMs in VMFS3 and VMFS5:

• For VMFS3, the supported RDM size depends on the underlying block size (2 TB - 512 bytes is the largest)
• In ESXi 5.0 and 5.1, VMFS5 supports up to 64 TB physical-mode RDMs
• In ESXi 5.5, VMFS5 supports up to 64 TB physical-mode RDMs and 62 TB virtual-mode RDMs

For more information, see Block size limitations of a VMFS datastore (1003565).

Block size limitations of a VMFS datastore
Frequently Asked Questions on VMware vSphere 5.x for VMFS-5