Overview

A virtio storage interface for efficient I/O that overcomes virtio-blk limitations and supports advanced SCSI hardware.

Features

Virtio device specification: part of VIRTIO 1.0
Linux guest driver: working
- Multi-queue / fine-grained per-queue locking
QEMU hardware emulation using SCSI emulation: working
- Added support for WRITE SAME commands
- Added support for hotplug events
QEMU hardware emulation using vhost-scsi: working
Libvirt support: working
SeaBIOS support: working
Tested use include:
- CD-ROM/DVD burning passthrough
- Tape passthrough
- 100s of LUNs (scalability)
- LUN hotplug (known to work with manual hotplug)

Pick up vhost-scsi work again:
- Port QEMU hw/virtio-scsi.c vhost-scsi support onto latest code
- add QEMU Object Model (QOM) support to the vhost-scsi device
- Port LIO vhost-scsi code onto latest lio.git code
- Update vhost-scsi to implement latest virtio-scsi device specification
- Ensure vhost-scsi I/O still works
- Design libvirt integration for LIO
QEMU SCSI target:
- Add support for rerror/werror to scsi-generic
Complete virtio-scsi spec implementation:
- Add support for asynchronous media change notifications
Use cases to flesh out:
- Multipath inside guest
Performance analysis
- Compare against virtio-blk I/O (rough numbers: 6% slower on iozone with a tmpfs-backed disk)
- Compare passthrough performance against bare metal host SCSI
- Measure scalability and where the bottlenecks are (full virtqueues? locks?)