On Thu, Nov 14, 2013 at 02:39:33AM -0500, Ayal Baron wrote:
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Hello Itamar. The specific use case is a particular propriety filesystem that needs to see a scsi device. It will do scsi inquiry conmmands to verify suitability. In talking to the devs - of the filesystem - there is no way around it. I'd previously tried virtio-block - resulting in the /dev/vd* device - and the filesystem would not work.
From doing a bit of web searching it appears the kvm/qemu supports (or did support) an emulated LSI scsi controller. My understanding is that the various virtualization platforms will emulate a well supported device (by the guest OSes) so that drivers are not an issue. For example this should allow a VM on Vmware vsphere/vcenter to be exported to Ovirt and have it boot up. The potential for further optimising the guest is there by installing ovirt/qemu/kvm guest utils that then allow the guest OS to understand the virtio nic and scsi devices. The guest could then be shut down, the nic and scsi controller changed and the guest booted up again. You can do the same thing in the Vmware world by installing their guest tools, shutting down the guest VM, then reconfiguring it with a vmxnet3 nic and pvscsi scsi adapter, then booting up again. It does seem somewhat inconsistent in Ovirt that we allow a choice of Intel e1000 or virtio nics, but do not offer any choice with the scsi adapter.
virtio-scsi support was just recently added to oVirt to allow for scsi passthrough and improved performance over virtio-blk. I believe the emulated scsi device in qemu never matured enough but possibly Stefan (cc'd) can correct me here.
The only supported emulated SCSI HBA device is virtio-scsi. It was Tech Preview in RHEL 6.3 and became fully supported in RHEL 6.4. virtio-scsi is not available in RHEL 5. Stefan