Hi,
Yes 6gb looks a little low - 2gb is the recommended bare minimum for esxi 5 - see http://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.install.doc_50%2FGUID-DEB8086A-306B-4239-BF76-E354679202FC.html
suspect with the 2gb the hypervisor has taken whatever is left is what you see there in the resource allocation tab
Many tx