Revision as of 09:43, 14 February 2012

Overview

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

Features

/dev/sda inside guest
Multiple LUNs per PCI adapter, solves virtio-blk 1:1 scalability problem
SCSI passthrough (tape, CD burning, ...)

Status

Virtio device specification
- Committed
- http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.4.pdf
Linux guest driver
- Patch on mailing list
- https://lkml.org/lkml/2012/2/5/75
QEMU hardware emulation using SCSI emulation
- Patches on mailing list
- http://www.spinics.net/lists/kvm/msg68444.html
QEMU hardware emulation using vhost-scsi
- (Stalled) work-in-progress, contact Stefan
- http://repo.or.cz/w/qemu/stefanha.git/shortlog/refs/heads/virtio-scsi
Libvirt support
- Patches on mailing list
- http://www.redhat.com/archives/libvir-list/2012-January/msg00537.html

Future tasks

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 WRITE SAME commands
- Add support for rerror/werror to scsi-generic
Complete virtio-scsi spec implementation:
- Add support for hotplug events
- Add support for asynchronous media change notifications
Use cases to flesh out:
- LUN hotplug
- CD-ROM/DVD burning passthrough
- Tape passthrough
- Multipath inside guest
- 100s of LUNs (scalability)
Performance analysis
- Compare against virtio-blk I/O
- Compare against bare metal host SCSI

Links

KVM Forum 2011 presentation Virtio SCSI: An alternative virtualized storage stack for KVM

@@ Line 2: / Line 2: @@
 A virtio storage interface for efficient I/O that overcomes virtio-blk limitations and supports advanced SCSI hardware.
+= Features =
+* /dev/sda inside guest
+* Multiple LUNs per PCI adapter, solves virtio-blk 1:1 scalability problem
+* SCSI passthrough (tape, CD burning, ...)
 = Status =
@@ Line 13: / Line 19: @@
 * QEMU hardware emulation using SCSI emulation
 ** Patches on mailing list
-** http://lists.gnu.org/archive/html/qemu-devel/2012-01/msg02012.html
+** http://www.spinics.net/lists/kvm/msg68444.html
 * QEMU hardware emulation using vhost-scsi
 ** (Stalled) work-in-progress, contact Stefan
@@ Line 23: / Line 29: @@
 = Future tasks =
 * Pick up vhost-scsi work again:
-** Port QEMU hw/virtio-scsi.c vhost-scsi support onto latest code; add QEMU Object Model (QOM) support
+** Port QEMU hw/virtio-scsi.c vhost-scsi support onto latest code
-** to the vhost-scsi device
+** add QEMU Object Model (QOM) support to the vhost-scsi device
-** Port LIO vhost-scsi code onto latest lio.git code and spec
+** 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
@@ Line 34: / Line 41: @@
 ** Add support for hotplug events
 ** Add support for asynchronous media change notifications
+* Use cases to flesh out:
-= Features =
+** LUN hotplug
+** CD-ROM/DVD burning passthrough
-* /dev/sda inside guest
+** Tape passthrough
-* Multiple LUNs per PCI adapter, solves virtio-blk 1:1 scalability problem
+** Multipath inside guest
-* SCSI passthrough (tape, CD burning, ...)
+** 100s of LUNs (scalability)
+* Performance analysis
+** Compare against virtio-blk I/O
+** Compare against bare metal host SCSI
 = Links =
 * KVM Forum 2011 presentation [http://www.linux-kvm.org/wiki/images/f/f5/2011-forum-virtio-scsi.pdf Virtio SCSI: An alternative virtualized storage stack for KVM]