f0b8204072
As discussed at our nova meetings, reorganize the juno specs into three directories: - proposed: things proposed which weren't approved - approved: things we approved but didn't implement - implemented: things approved and implemented The first I suspect is the most controversial. I've done this because I worry about the case where a future developer wants to pick up something dropped by a previous developer, but has trouble finding previous proposed specifications on the topic. Note that the actual proposed specs for Juno are adding in a later commit. Change-Id: Idcf55ca37a83d7098dcb7c2971240c4e8fd23dc8
3.0 KiB
Add virtio-scsi bus support for block device mapping
https://blueprints.launchpad.net/nova/+spec/add-virtio-scsi-bus-for-bdm
VirtIO SCSI is a new para-virtualized SCSI controller device for KVM instances. It has been designed to replace virtio-blk, increase it's performance and improve scalability. Currently, using virtio-scsi bus is not supported when booting from volume.
Problem description
VirtIO SCSI is a new para-virtualized SCSI controller device for KVM instances. It has been designed to replace virtio-blk, increase it's performance and improve scalability. The interface is capable of handling multiple block devices per virtual SCSI adapter, keeps the standard scsi device naming in the guests (e.x /dev/sda) and support SCSI devices passthrough.
Currently, virtio-scsi bus has been supported when booting from glance image, which is implemented by BP ([1]) aimed to Icehouse.
However, when we create a cinder volume from this image, and then booting from this volume and specify the bus_type as "scsi", the guest will still use lsi controller instead of virtio-scsi controller.
The aim of this BP as follows:
When booting from volume with "scsi" bus type, use virtio-scsi controller for volume which was created from glance image, which is set with "virtio-scsi" hw_scsi_model property.
The main use case is to improve performance in I/O-intensive applications.
Proposed change
- Nova retrieve "hw_scsi_model" property from volume's glance_image_metadata when booting from cinder volume
- Libvirt driver will create the "virtio-scsi" controller if "hw_scsi_model" property is "virtio-scsi" and the bus_type specified for volume is "scsi"
Alternatives
None
Data model impact
None
REST API impact
None
Security impact
None
Notifications impact
None
Other end user impact
None
Performance Impact
Will improve guest's performance.
Other deployer impact
None
Developer impact
None
Implementation
Assignee(s)
- Primary assignee:
Work Items
- Nova retrieve "hw_scsi_model" property from volume's glance_image_metadata when booting from cinder volume
- Libvirt driver will create the "virtio-scsi" controller if "hw_scsi_model" property is "virtio-scsi" and the bus_type specified for volume is "scsi"
Dependencies
- Depend on the BP [1], which will provide the virtio-scsi-controller object
Testing
None
Documentation Impact
None