openstack/cinderlib
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cinderlib/doc/source/limitations.rst
Gorka Eguileor 77f399fd96 Format as a Cinder-related OpenStack project 
Since we are going to be importing the project into OpenStack we need it
to follow the same structure as the other projects under the Cinder
umbrella.
2019-02-19 16:28:03 +01:00

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Limitations

Cinderlib works around a number of issues that were preventing the usage of the drivers by other Python applications, some of these are:

  • Oslo config configuration loading.
  • Cinder-volume dynamic configuration loading.
  • Privileged helper service.
  • DLM configuration.
  • Disabling of cinder logging.
  • Direct DB access within drivers.
  • Oslo Versioned Objects DB access methods such as refresh and save.
  • Circular references in Oslo Versioned Objects for serialization.
  • Using multiple drivers in the same process.

Being in its early development stages, the library is in no way close to the robustness or feature richness that the Cinder project provides. Some of the more noticeable limitations one should be aware of are:

  • Most methods don't perform argument validation so it's a classic GIGO library.
  • The logic has been kept to a minimum and higher functioning logic is expected to be handled by the caller: Quotas, tenant control, migration, etc.
  • Limited test coverage.
  • Only a subset of Cinder available operations are supported by the library.

Besides cinderlib's own limitations the library also inherits some from Cinder's code and will be bound by the same restrictions and behaviors of the drivers as if they were running under the standard Cinder services. The most notorious ones are:

  • Dependency on the eventlet library.
  • Behavior inconsistency on some operations across drivers. For example you can find drivers where cloning is a cheap operation performed by the storage array whereas other will actually create a new volume, attach the source and new volume and perform a full copy of the data.
  • External dependencies must be handled manually. So users will have to take care of any library, package, or CLI tool that is required by the driver.
  • Relies on command execution via sudo for attach/detach operations as well as some CLI tools.