Q. Does a pass-through disk with Hyper-V have to be direct attached storage on the Hyper-V host?

A. No. A pass-through disk is any storage that is accessible to the Hyper-V server, such as direct attached or a LUN on a Storage Area Network. Remember that regardless of where the storage is, it must be offline on the actual Hyper-V server before the guest can be configured to access it via pass-through. Also remember that the entire disk is mapped to a guest, not a volume on the disk. Finally, the disk must be initialized before it can be used for pass-through, so if the disk isn't initialized then initialize it on the Hyper-V host then place it in an offline status so it can be used for pass-through.

Normally you use Virtual Hard Disks for virtual machine storage. When configured as fixed size, VHDs perform almost identically to pass-through storage, and you lose features such as snap-shotting when using pass-through, so always try and use VHD above pass-through.

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