diff options
| author | Kevin Wolf <kwolf@redhat.com> | 2023-09-01 12:24:30 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2023-09-08 17:03:09 +0200 |
| commit | a675ca4c620e66c1d45d55037f8fc21286af58cd (patch) | |
| tree | db55e93aef9cdebcd87ba574c46a1212e056fd4e /docs/tools | |
| parent | 816248675a21d5b4d82f22a6a19ddd2a7fbfee18 (diff) | |
qemu-img: Update documentation for compressed images
Document the 'compression_type' option for qcow2, and mention that
streamOptimized vmdk supports compression, too.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230901102430.23856-1-kwolf@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'docs/tools')
| -rw-r--r-- | docs/tools/qemu-img.rst | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst index 15aeddc6d8..ca5a2773cf 100644 --- a/docs/tools/qemu-img.rst +++ b/docs/tools/qemu-img.rst @@ -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. |