>>quickscanning the code turned up no gotchas for me - as you isolated a stream and CRC that, first impulse is to suspect versioning. As this sounds stupid as well, setting up VMs with Dotnet 4.5 and another, older one and to compare CRC results done from "local VM system disc" and shared drives would be next step for me. PITA...
>
>Yes, that is pretty much what I had in my agenda for tomorrow.
>
>Quick correction however, what I meant was that the file size on disk differs in the new environment and that doing a CRC32 on a file size which is different from one environment to another, for the same file, will thus create a different CRC32.
>
>So, this leads to think that the problem is in fact the storage mechanism on the NAS. I will verify the file size recognized from Windows on a file stored on the C: drive and the same file stored on the NAS.

Disclaimer: I'm not a NetApp user.

Google found a useful link for reported file size differences: https://communities.netapp.com/thread/10833 . I don't know if that applies in your case, it seems that link talks about what you see in Windows Explorer vs. what you see in a native NetApp equivalent.

In a much smaller, less sophisticated environment I ran into a problem trying to get Windows Server 2012 "Windows Server" backups to be stored on a QNAP NAS. Although I ended up saving the backups to another non-NAS location I did find out the problem apparently is the NAS does not by default support NTFS sparse files (although this can be enabled).

If the files you've copied to the new environment are sparse that *might* be a problem. It seems NetApp supports NTFS/CIFS sparse files ( https://communities.netapp.com/servlet/JiveServlet/download/110068-45010/tr-3367_Netapp_Storage_Sys_in_Microsoft_Windows_Environment.pdf ) but I have no idea if that support is enabled by default or is enabled in your particular environment. Again, I believe this would only apply if your files are sparse.

You can query the sparse status of a file with http://superuser.com/questions/508801/removing-sparse-file-attribute .

There is some technical information at http://blogs.msdn.com/b/openspecification/archive/2010/11/05/notes-on-sparse-files-and-file-sharing.aspx .