A. NAS devices are typically accessed via SMB (file level), which means from the Hyper-V server you’d be accessing a UNC path such as \\server\share. Hyper-V version 1 allowed this type of access, though it was never officially supported. With Hyper-V R2 (with Windows 2008 R2) RTM, UNC paths won't work and aren't supported.
If you want to use external storage with Hyper-V, such as a SAN, the storage must be locally mounted on the Hyper-V server or be part of a Cluster Shared Volume, which allows direct NTFS access. This means you need to connect via iSCSI or something like Fibre Channel (FC), which then allow you to format the partition as NTFS locally on the Hyper-V server and access at a block level. Hyper-V only supports block level access with Windows 2008 and Windows 2008 R2 RTM.
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