Several issues around VSS based protection & recovery are being addressed with this Hyper-V update rollup package KB975354. The last three issues might sound familiar if you already perform host level protection of virtual machines on Cluster Shared Volumes (CSV) with Microsoft System Center Data Protection Manager 2010. Issue 1: Some Internet SCSI (iSCSI) connections’re created in a vm running Windows Server 2003. You back up this vm on virtual machine host server. In this scenario, error code 0×800423f4 occurs when you back up vm. dditionally, following event’s logged into Hyper-V Virtual Machine Management Service event log: The number of reverted volumes does not match the number of volumes in the snapshot set for virtual machine “’virtual machine name’ (Virtual machine ID <GUID>)”.