Not supported last time I checked.  Hyper-V requires specific components of SMBv3.0 that last I heard had not yet been implemented.  That certainly could have changed recently, so you all can correct me if I'm wrong.  But in general it's a really bad idea.  Why?  Because a .VHD file, like a .VMDK file for Vmware is a single large file.  Data is protected on Isilon at the file level, not at the block level.  Also read-ahead caching on Isilon isn't going to work terribly well within a single large file when you have random reads.  Put this workload on a block array like Unity over iSCSI or FC, not on Isilon over SMB.  Also Isilon has a max file size limit of 4TB, so no one file (or drive) could ever be more than 4TB.

~Chris