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[PULL 08/14] qemu-img: Update documentation for compressed images
From: |
Kevin Wolf |
Subject: |
[PULL 08/14] qemu-img: Update documentation for compressed images |
Date: |
Mon, 4 Sep 2023 16:36:37 +0200 |
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>
---
docs/tools/qemu-img.rst | 19 +++++++++++++++++--
1 file 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.
--
2.41.0
- [PULL 00/14] Block layer patches, Kevin Wolf, 2023/09/04
- [PULL 02/14] iotests: adapt test output for new qemu_cleanup() behavior, Kevin Wolf, 2023/09/04
- [PULL 01/14] block/vpc: Avoid dynamic stack allocation, Kevin Wolf, 2023/09/04
- [PULL 03/14] block: minimize bs->reqs_lock section in tracked_request_end(), Kevin Wolf, 2023/09/04
- [PULL 04/14] block: change reqs_lock to QemuMutex, Kevin Wolf, 2023/09/04
- [PULL 06/14] block/iscsi: Document why we use raw malloc(), Kevin Wolf, 2023/09/04
- [PULL 07/14] block: Be more verbose in create fallback, Kevin Wolf, 2023/09/04
- [PULL 05/14] qemu-img: omit errno value in error message, Kevin Wolf, 2023/09/04
- [PULL 09/14] vmdk: Clean up bdrv_open_child() return value check, Kevin Wolf, 2023/09/04
- [PULL 08/14] qemu-img: Update documentation for compressed images,
Kevin Wolf <=
- [PULL 10/14] block: remove AIOCBInfo->get_aio_context(), Kevin Wolf, 2023/09/04
- [PULL 13/14] block: Remove bdrv_query_block_node_info, Kevin Wolf, 2023/09/04
- [PULL 14/14] block: Remove unnecessary variable in bdrv_block_device_info, Kevin Wolf, 2023/09/04
- [PULL 11/14] block-backend: process I/O in the current AioContext, Kevin Wolf, 2023/09/04
- [PULL 12/14] block-backend: process zoned requests in the current AioContext, Kevin Wolf, 2023/09/04
- Re: [PULL 00/14] Block layer patches, Stefan Hajnoczi, 2023/09/06