cinder/releasenotes/notes/leverage-compression-accele...

50 lines
2.4 KiB
YAML

---
features:
- |
A general framework to accommodate hardware compression accelerators for
compression of volumes uploaded to the Image service (Glance) as images
and decompression of compressed images used to create volumes is
introduced.
The only accelerator supported in this release is Intel QuickAssist
Technology (QAT), which produces a compressed file in gzip format.
Refer to this `Cinder documentation
<https://docs.openstack.org/cinder/latest/admin/blockstorage-accelerate-image-compression.html>`_
for more information about using this feature.
Additionally, the framework provides software-based compression using
GUNzip tool if a suitable hardware accelerator is not available.
Because this software fallback could cause performance problems if the
Cinder services are not deployed on sufficiently powerful nodes, the
default setting is *not* to enable compression on image upload or
download.
The compressed image of a volume will be stored in the
Image service (Glance) with the ``container_format`` image property of
``compressed``. See the `Image service documentation
<https://docs.openstack.org/glance/latest>`_ for more information about
this image container format.
issues:
- |
In the Image service (Glance), the ``compressed`` container format
identifier does not indicate a particular compression technology; it is up
to the image consumer to determine what compression has been used, and
there is no requirement that OpenStack services must support arbitrary
compression technologies. For the upload and download of compressed
images, Cinder supports *only* the gzip format.
While you may expect that Cinder will be able to consume any image in
``compressed`` container format *that Cinder has created*, you should not
expect Cinder to be able to successfully use an image in ``compressed``
format that it has not created itself.
upgrade:
- |
Added string config option ``compression_format`` in [default] section of
cinder.conf to specify image compression format. Currently the only legal
value for this option is ``gzip``.
- |
Added boolean config option ``allow_compression_on_image_upload`` in
[default] section of cinder.conf to enable/disable image compression on
image upload. The default value of this option is ``false``, which means
image compression is disabled.