Sometimes creating a new snapshot of a virtual machine or performing a convertion process with VMware vCenter Converter you get the error:

      File is larger than the maximum size supported by datastore

This message tells us that we are trying to create a file that is bigger than the maximum size supported by the file system. The maximum size for a file is determined by the block size that we choose during the format of the volume as VMFs in order to create a new datastore.

For ejample if we choose a block size of 1MB the largest file that we will be able to create on that VMFS is of 256GB and if we have a vmdk file (virtual disk file) of that size and try to create a snapshot of it we will need an aditional space of 2GB to store the deltas and that will move our file from 256GB to 258GB and it will be bigger than the maximum supported by a VMFS with a block size of 1MB.

In order to workaround this move the virtual machine to a VMFS volume with 2MB block size.

The issue affects all virtual disks having the maximum size permitted by VMFS.

If you need more information about file system maximums visit the following documents:

• VMware® vSphere 4.0 – Configuration Maximums
• VMware Infrastructure 3 – Configuration Maximums