KVMotion: conductor eph support#647
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Problem Cross-HV resize previously required the instance to be BFV, enforced by a global precondition in raise_on_unsupported_cross_hypervisor_resize. Image-backed instances with an ephemeral root disk were always rejected before scheduling. Solution Remove the BFV-only precondition from the utility function. Add conductor-local guards that enforce the allowed root BDM shapes after scheduling so the removal does not open the path to unsupported cases: - image/local (ephemeral) passes through to the conversion path - */volume (already BFV) passes through to the existing BFV-only path - any other root shape (e.g. blank/local, missing root BDM) is rejected A cross-cell scheduler selection is also rejected for cross-HV resize: the source-side preparation RPCs are cell-local, so cross-cell placement is not viable. Change-Id: Ib66d7de2da1865437b0db9a2127cfd928c3ab073
Problem KVM hosts cannot boot from a Nova-managed VMDK on a VMware ephemeral datastore. Before the existing BFV-only cross-HV resize path can handle an image-backed instance, the root disk must be moved to Cinder. Solution After scheduling selects a KVM destination, MigrationTask._execute() checks whether the root BDM is image/local and if so runs a conversion pre-step before prep_resize is dispatched. The pre-step calls prep_cross_hv_conversion on the source compute to power off the guest and detach the root VMDK, then calls volume_api.manage_existing to import the VMDK as a Cinder FCD volume. The manage ref includes source-name (datastore path), size_gb (rounded up from size_bytes), and an optional source-id when the VMDK already has an FCD id. Once the volume is available, a reserved attachment is created, the root BDM is mutated to destination_type=volume, and system_metadata is updated to record the conversion. The instance then proceeds through the existing BFV-only path unchanged. The conversion is permanent. Revert undoes the resize but the instance comes back as BFV-on-VMware rather than returning to ephemeral. Point-of-no-return: once Cinder's manage_existing initiates relocation of the VMDK from VMFS to the FCD NFS pool, the source disk is gone. Abort (re-attach + power on) is only called when the observed terminal volume state is 'error', which confirms relocation did not occur. A generic exception from manage_existing or a volume in 'error_managing' does not trigger abort, as either could mean relocation has already started. Change-Id: I7e991b5da895b059a5b9f459c44ad3e4d5f93c3d
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