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| − | == The Better Path To Live Migration and Resizing ==
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| − | === Rationale ===
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| − | The current code path for resizing and live migration is what you could call ''hairy'' in that the state-machine that is used to accomplish these 2 types of tasks (which are by there very nature extremely similar) is itself complex and could benefit from rework around a more organized state-machine which would be orchestrated by an external entity, of which said external entity can handle the intricacies of cross-compute communication as well as state-machine transitions and associated failure scenarios. This will make said operation more reliable and centralize the orchestration of said operations to a single entity, which instead of having multiple functions, one or 2 may suffice. Therefore the complexity of code reviews and understanding the complexity of said operations becomes lower and makes them easier to [test, modify, understand].
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| − | === Definitions ===
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| − | ;Live migration
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| − | : Moving a instance (and associated) resources from one compute node to another compute node while the instance is still '''running'''.
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| − | ;Resizing
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| − | : Moving a '''powered-off''' instance (and associated) resources from one compute node to another compute node which can support the instance with re-sized capabilities (more/less VCPU for example).
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| − | === Current path ===
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| − | ==== Live migrate simple ====
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| − | [[File:Live-migrate-happy.png|400px|thumb|]]
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| − | ==== Live migrate (volume backed) ====
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| − | [[File:Live_migrate.png|400px|thumb|]]
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| − | ==== The problems ====
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| − | === Better path ===
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| − | ==== What changes ====
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| − | === Migration from current to better ===
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| − | === Bugs/blueprints ===
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