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 in Train release.

The only accelerator supported in this release is Intel QuickAssist
Technology (QAT), which produces a compressed file in gzip format.
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 for more information about this image container
format.

Configure image compression

To enable the image compression feature, set the following
configuration option in the cinder.conf file:

allow_compression_on_image_upload = True

By default it will be set to False, which means image compression is
disabled.

compression_format = gzip

This is to specify image compression format. The only supported
format is gzip in Train release.

System requirement

In order to use this feature, there should be a hardware accelerator
existing in system, otherwise no benefit will get from this feature.
Regarding the two accelerators that supported, system should be
configured as below:

• Intel QuickAssist Technology (QAT) – This is the
  hardware accelerator from Intel. The driver of QAT should be installed,
  refer to https://01.org/intel-quickassist-technology.
  Also the compression library QATzip should be installed, refer to https://github.com/intel/QATzip.
• GUNzip – The related package of GUNzip
  should be installed and the command gzip should be
  available. This is used as fallback when hardware accelerator is not
  available.