@@ -59,13 +59,27 @@ options that are supported for it.
.. option:: qcow2
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), zlib based compression and support of multiple VM
+ images (useful if your filesystem does not support holes, for example
+ on Windows), zlib/zstd compression and support of multiple VM
snapshots.
- Supported options:
+ Supported create options:
.. program:: qcow2
+ .. option:: backing_file
+
+ File name of a base image (see ``create`` subcommand)
+
+ .. option:: backing_fmt
+
+ Image format of the base image
+
+ .. option:: cluster_size
+
+ Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
+ sizes can improve the image file size whereas larger cluster sizes generally
+ provide better performance.
+
.. option:: compat
Determines the qcow2 version to use. ``compat=0.10`` uses the
@@ -74,13 +88,9 @@ options that are supported for it.
newer understand (this is the default). Amongst others, this includes
zero clusters, which allow efficient copy-on-read for sparse images.
- .. option:: backing_file
+ .. option:: compression_type
- File name of a base image (see ``create`` subcommand)
-
- .. option:: backing_fmt
-
- Image format of the base image
+ Selects the compression algorithm (zlib or zstd).
.. option:: encryption
@@ -150,19 +160,11 @@ options that are supported for it.
Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
Defaults to ``2000``. Only used when ``encrypt.format=luks``.
- .. option:: cluster_size
+ .. option:: extended_l2
- Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
- sizes can improve the image file size whereas larger cluster sizes generally
- provide better performance.
-
- .. option:: preallocation
-
- Preallocation mode (allowed values: ``off``, ``metadata``, ``falloc``,
- ``full``). An image with preallocated metadata is initially larger but can
- improve performance when the image needs to grow. ``falloc`` and ``full``
- preallocations are like the same options of ``raw`` format, but sets up
- metadata also.
+ Enables the Extended L2 Entries feature that divides each cluster into 32
+ separately allocated sub-clusters. A larger cluster size can be used, thus
+ reducing metadata overhead, while still allowing fine-grained allocation.
.. option:: lazy_refcounts
@@ -196,6 +198,53 @@ options that are supported for it.
filename`` to check if the NOCOW flag is set or not (Capital 'C' is
NOCOW flag).
+ .. option:: preallocation
+
+ Preallocation mode (allowed values: ``off``, ``metadata``, ``falloc``,
+ ``full``). An image with preallocated metadata is initially larger but can
+ improve performance when the image needs to grow. ``falloc`` and ``full``
+ preallocations are like the same options of ``raw`` format, but sets up
+ metadata also.
+
+ Supported runtime options:
+
+ .. program:: qcow2
+ .. option:: cache-clean-interval
+
+ Clean unused cache entries after this time (in seconds).
+
+ .. option:: cache-size
+
+ Maximum combined metadata (L2 tables and refcount blocks) cache size.
+
+ .. option:: encrypt.key-secret
+
+ ID of secret providing qcow2 AES key or LUKS passphrase.
+
+ .. option:: l2-cache-size
+
+ Maximum L2 table cache size.
+
+ .. option:: l2-cache-entry-size
+
+ Size of each entry in the L2 cache.
+
+ .. option:: pass-discard-request
+
+ Pass guest discard requests to the layer below (on/off).
+
+ .. option:: pass-discard-snapshot
+
+ Generate discard requests when snapshot related space is freed (on/off).
+
+ .. option:: pass-discard-other
+
+ Generate discard requests when other clusters are freed (on/off).
+
+ .. option:: refcount-cache-size
+
+ Maximum refcount block cache size.
+
.. program:: image-formats
.. option:: qed
Put the create options in alphabetical order, add compression_type and extended_l2, and also mention the common runtime options. I did not add rarely-used runtime options because I think it's too much information. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- docs/system/qemu-block-drivers.rst.inc | 91 ++++++++++++++++++++------ 1 file changed, 70 insertions(+), 21 deletions(-)