Enhancements to the Nova XCP Plugin to Support Volume Backed Storage Repositories
When loading an OVA image from the Glance repository existing Nova support for Xen relies on the mounted, file system presence of the XCP storage repository. HBA mediated volume storage support in XCP does not mount its volumes within the XCP/Dom0 file system space. It is proposed that the Nova Xen Plugin implementation be modified to rely on "xe" commands to create and manipulate virtual disk images. Where data copies are needed, Linux "dd" commands into the underlying devices can be done. In this way all Xen storage repository types can be supported and reliance on Xen implementation details can be eliminated.
Blueprint information
- Status:
- Complete
- Approver:
- None
- Priority:
- Undefined
- Drafter:
- None
- Direction:
- Needs approval
- Assignee:
- None
- Definition:
- Obsolete
- Series goal:
- None
- Implementation:
-
Unknown
- Milestone target:
- None
- Started by
- Completed by
- Vish Ishaya
Whiteboard
Some features, like resize, currently require access to the raw VHD file to work.
All operations xe can do should be possible directly using XenAPI, so there is unlikely to be a need for a plugin.
However, it is not clear to me that all the operations can be performed directly using XenAPI. I think the extra work required is around converting the contents of a volume into a file. This work is bypassed when using EXT storage, but getting hold of the file that is on disk.
I think a good first step would be to look at supporting LVM local storage, but still allowing the "optimizations" currently used with EXT storage, when they are possible. We need to decide if this is useful to enough people.
An alternative is to be clear about what works with Volumes, and what works with local storage, and what works with VMs on shared storage not managed using nova-volume.
