Add spec to optimize upload volume for RBD backend
This patch adds the spec for optimizing the path when we are uploading a volume from RBD backend to glance RBD store. Implements: blueprint optimize-upload-volume-to-rbd-store Change-Id: I7bfc41b9594b8b7fbc6228973c3c276aa1cf5427
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Rajat Dhasmana
whoami-rajat
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specs/yoga/optimize-upload-volume-to-rbd-store.rst
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specs/yoga/optimize-upload-volume-to-rbd-store.rst
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..
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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==============================================
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Optimze upload volume to image for RBD backend
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==============================================
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https://blueprints.launchpad.net/cinder/+spec/optimize-upload-volume-to-rbd-store
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This spec proposes to optimize the upload volume to image operation from cinder
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rbd backend to glance rbd store by using COW cloning.
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Problem description
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-------------------
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Currently when doing a upload volume to image operation and the source (cinder)
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and destination (glance) backends are rbd, we don't have any optimization
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and the generic code path to copy data chunk by chunk is executed.
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This can be improved by doing a COW clone as we do it incase of creating volume
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from image [1]_.
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Use Cases
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---------
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We want to improve the performance when uploading a volume from cinder rbd backend
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to glance rbd store using COW cloning.
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Proposed change
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---------------
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The changes will be needed on both glance and cinder side.
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1) Glance
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Expose store type and rbd specific store info (like rbd pool name for glance
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in this case) via stores info API [2]_.
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This can be extended to other stores by providing store specific details with
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the stores info API like we do with get pools API [3]_ on cinder side.
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Further information regarding its implementation can be provided with a
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glance side spec.
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2) Cinder
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Get the stores info from Glance and find the default store.
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If the glance default store is ``rbd`` and cinder is using ``rbd`` backend to
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upload the volume to image then we will proceed with the COW clone operation
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from the volume pool to the images pool (pool name provided by glance) and
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register the image location on glance side.
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We will also introduce a new config parameter ``enable_clone_optimization`` to
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enable/disable this optimization on cinder side. More information about it
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can be found in `Security impact`_ section.
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Alternatives
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------------
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None
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Data model impact
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-----------------
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None
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REST API impact
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---------------
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None. This is RBD driver specific feature.
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Security impact
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---------------
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Since this optimization skips the writing of image that happens on the glance side, it will
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also skip the checksum and hash value calculated in that scenario.
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We will introduce a new config parameter ``enable_clone_optimization`` to enable/disable
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this optimization and also mention the security risks that comes with enabling it. By default,
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it will be disabled.
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Active/Active HA impact
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-----------------------
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None
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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None
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Performance Impact
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------------------
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Uploading volume to image in case of cinder RBD to glance RBD will be
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significantly improved.
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+------------------------------------+---------------+---------------+---------------+
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| Image size | 2GB | 3GB | 5GB |
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+====================================+===============+===============+===============+
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| Time without COW clone | 1min17Sec | 1min15Sec | 2min49Sec |
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+------------------------------------+---------------+---------------+---------------+
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| Time with COW clone | 1.29Sec | 2.32Sec | 1.63Sec |
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+------------------------------------+---------------+---------------+---------------+
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| | **-98%** | **-97%** | **-99%** |
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+------------------------------------+---------------+---------------+---------------+
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Other deployer impact
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---------------------
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The Cinder service user will need to have read and write to the Glance pool.
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Note that Read access might already be granted and only write access needs
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to be provided.
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Developer impact
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----------------
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None
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Implementation
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--------------
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Assignee(s)
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~~~~~~~~~~~
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Primary assignee:
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Rajat Dhasmana (whoami-rajat)
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Work Items
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~~~~~~~~~~
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- Query glance for stores info (After exposing details from glance side)
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- Do a COW clone if the volume to be uploaded is in glance RBD store
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(volume is uploaded in glance default store)
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Dependencies
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~~~~~~~~~~~~
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Glance side changes are required to expose store type and RBD store info
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like glance pool name.
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Testing
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~~~~~~~
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* Unit tests
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* Tempest or manual testing for checking if RBD image dependency blocks
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deletion of source resource
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* Upload volume to image
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* Delete the original volume
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AND
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* Upload volume to image
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* Create volume from image
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* Delete the image
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Documentation Impact
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~~~~~~~~~~~~~~~~~~~~
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None
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References
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----------
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.. [1] https://opendev.org/openstack/cinder/commit/edc11101cbc06bdce95b10cfd00a4849f6c01b33
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.. [2] https://docs.openstack.org/api-ref/image/v2/index.html?expanded=list-stores-detail#list-stores
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.. [3] https://docs.openstack.org/api-ref/block-storage/v3/?expanded=list-all-back-end-storage-pools-detail#list-all-back-end-storage-pools
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@ -1,6 +0,0 @@
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.. This file is a place holder. It should be removed by
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any patch proposing a spec for the Wallaby release
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================================
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No specs have yet been approved.
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================================
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