Software-Only Setup to Diagnose QEMU SCSI Passthrough and Multipath Failover

The SCSI passthrough over multipath is very commonly used in virtualization environments. The SCSI IO commands are forwarded from the virtual machine to the KVM hypervisor side storage via SG_IO. The KVM hypervisor side storage is always provied in a multipath configuration in order to facilitate high availability. Therefore, the developers may require a solution that allows them to quickly and efficiently setup an environment to diagnose and observe the behavior of virtio-scsi + QEMU + SG_IO + multipath + SCSI, e.g., how the path error is propagated to the virtual machine.