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 filesThis 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.