ef9f435679
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
4.9 KiB
Optimze upload volume to image for RBD backend
https://blueprints.launchpad.net/cinder/+spec/optimize-upload-volume-to-rbd-store
This spec proposes to optimize the upload volume to image operation from cinder rbd backend to glance rbd store by using COW cloning.
Problem description
Currently when doing a upload volume to image operation and the source (cinder) and destination (glance) backends are rbd, we don't have any optimization and the generic code path to copy data chunk by chunk is executed. This can be improved by doing a COW clone as we do it incase of creating volume from image1.
Use Cases
We want to improve the performance when uploading a volume from cinder rbd backend to glance rbd store using COW cloning.
Proposed change
The changes will be needed on both glance and cinder side.
- Glance
Expose store type and rbd specific store info (like rbd pool name for glance in this case) via stores info API2. This can be extended to other stores by providing store specific details with the stores info API like we do with get pools API3 on cinder side. Further information regarding its implementation can be provided with a glance side spec.
- Cinder
Get the stores info from Glance and find the default store. If the
glance default store is rbd and cinder is using
rbd backend to upload the volume to image then we will
proceed with the COW clone operation from the volume pool to the images
pool (pool name provided by glance) and register the image location on
glance side.
We will also introduce a new config parameter
enable_clone_optimization to enable/disable this
optimization on cinder side. More information about it can be found in
Security impact section.
Alternatives
None
Data model impact
None
REST API impact
None. This is RBD driver specific feature.
Security impact
Since this optimization skips the writing of image that happens on
the glance side, it will also skip the checksum and hash value
calculated in that scenario. We will introduce a new config parameter
enable_clone_optimization to enable/disable this
optimization and also mention the security risks that comes with
enabling it. By default, it will be disabled.
Active/Active HA impact
None
Notifications impact
None
Other end user impact
None
Performance Impact
Uploading volume to image in case of cinder RBD to glance RBD will be significantly improved.
| Image size | 2GB | 3GB | 5GB |
|---|---|---|---|
| Time without COW clone | 1min17Sec | 1min15Sec | 2min49Sec |
| Time with COW clone | 1.29Sec | 2.32Sec | 1.63Sec |
| -98% | -97% | -99% |
Other deployer impact
The Cinder service user will need to have read and write to the Glance pool. Note that Read access might already be granted and only write access needs to be provided.
Developer impact
None
Implementation
Assignee(s)
- Primary assignee:
-
Rajat Dhasmana (whoami-rajat)
Work Items
- Query glance for stores info (After exposing details from glance side)
- Do a COW clone if the volume to be uploaded is in glance RBD store (volume is uploaded in glance default store)
Dependencies
Glance side changes are required to expose store type and RBD store info like glance pool name.
Testing
Unit tests
Tempest or manual testing for checking if RBD image dependency blocks deletion of source resource
- Upload volume to image
- Delete the original volume
AND
- Upload volume to image
- Create volume from image
- Delete the image
Documentation Impact
None
References
https://opendev.org/openstack/cinder/commit/edc11101cbc06bdce95b10cfd00a4849f6c01b33↩︎
https://docs.openstack.org/api-ref/image/v2/index.html?expanded=list-stores-detail#list-stores↩︎
https://docs.openstack.org/api-ref/block-storage/v3/?expanded=list-all-back-end-storage-pools-detail#list-all-back-end-storage-pools↩︎