The hv_storvsc driver implements the virtual store device for FreeBSD guest partitions running on Hyper-
V. FreeBSD guest partitions running on Hyper-V do not have direct access to storage devices attached to
the Hyper-V server. Although a FreeBSD guest can access storage devices using Hyper-V's full emulation
mode, the performance in this mode tends to be unsatisfactory.
To counter the above issues, the hv_storvsc driver implements a storage Virtual Service Consumer (VSC)
that relays storage requests from the guest partition to the storage Virtual Service Provider (VSP)
hosted in the root partition using the high performance data exchange infrastructure provided by
hv_vmbus(4) driver. The VSP in the root partition then forwards the storage related requests to the
physical storage device.
This driver functions by presenting a SCSI HBA interface to the Comman Access Method (CAM) layer. CAM
control blocks (CCBs) are converted into VSCSI protocol messages which are delivered to the root
partition VSP over the Hyper-V VMBus.