What you need to do, is to create a virtual machine with virtual disks for the data, in the size you need. The VM can then be configured like a typical (physical) file server. Please keep in mind that virtual disks have a size limit (see my previous post) and you will need to create at least two virtual disks to take advantage of the diskspace on the datastore. Also leave some fee disk space for e.g. snapshots, logfiles, swapfiles, ... With the disk size you mentioned, I'd suggest to keep about 10%-15% free.
André