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http://searchstorage.techtarget.co.uk/feature/Block-vs-file-for-Hyper-V-and-VMware-storage-Which-is-better
http://searchservervirtualization.techtarget.com/tip/ISCSI-vs-NFS-for-virtualization-shared-storage
http://www.enterpriseefficiency.com/author.asp?section_id=2219&doc_id=248399