Virtual SCSI devices
Virtual SCSI host bus adapters (HBAs) enable guests to access virtual SCSI
devices within virtual servers. Virtual SCSI HBAs
are virtio devices that are provided by the KVM hypervisor and do not map to physical FCP devices on the host.
Virtual SCSI devices, in contrast, can map to SCSI devices or other resources on the host. Figure 1 illustrates two common mappings for
virtual SCSI devices:
- A LUN for a SCSI-attached tape drive on the host.
- A DVD ISO file on the host file system.
In this publication, a virtual SCSI device on the guest that is backed by a SCSI device on the host is called a SCSI pass-through device. Do not confuse SCSI pass-through with VFIO pass-through. With SCSI pass-through, the SCSI device on the host and the virtual SCSI device on the guest are different devices.
Configure virtual SCSI devices only if you need to address the device through SCSI-specific interfaces. In particular, configure SCSI disks as virtual block devices rather than virtual SCSI devices.