@@ -106,7 +106,11 @@ by the used format or see the format descriptions below for details.
.. option:: -c
- Indicates that target image must be compressed (qcow format only).
+ Indicates that target image must be compressed (qcow/qcow2 and vmdk with
+ streamOptimized subformat only).
+
+ For qcow2, the compression algorithm can be specified with the ``-o
+ compression_type=...`` option (see below).
.. option:: -h
@@ -776,7 +780,7 @@ Supported image file formats:
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
- on Windows), optional AES encryption, zlib based compression and
+ on Windows), optional AES encryption, zlib or zstd based compression and
support of multiple VM snapshots.
Supported options:
@@ -794,6 +798,17 @@ Supported image file formats:
``backing_fmt``
Image format of the base image
+ ``compression_type``
+ This option configures which compression algorithm will be used for
+ compressed clusters on the image. Note that setting this option doesn't yet
+ cause the image to actually receive compressed writes. It is most commonly
+ used with the ``-c`` option of ``qemu-img convert``, but can also be used
+ with the ``compress`` filter driver or backup block jobs with compression
+ enabled.
+
+ Valid values are ``zlib`` and ``zstd``. For images that use
+ ``compat=0.10``, only ``zlib`` compression is available.
+
``encryption``
If this option is set to ``on``, the image is encrypted with
128-bit AES-CBC.