DescriptionRichard W.M. Jones
2023-08-31 13:35:13 UTC
Description of problem:
qcow2 supports compressed images. The default is zlib, but zstd is
also supported upstream. However zstd compression is not enabled
in RHEL qemu-kvm at all, meaning that we cannot create, open etc
qcow2 zstd-compressed images.
Fedora and other distributions may switch to zstd compression for
qcow2, and this will create an interoperability issue in future.
Version-Release number of selected component (if applicable):
qemu-img-8.0.0-7.el9.x86_64
How reproducible:
100%
Steps to Reproduce:
$ qemu-img create -f qcow2 test.qcow2 1G -o compression_type=zstd
Formatting 'test.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zstd size=1073741824 lazy_refcounts=off refcount_bits=16
qemu-img: test.qcow2: Parameter 'compression-type' does not accept value 'zstd'
On Fedora this works:
$ qemu-img create -f qcow2 test.qcow2 1G -o compression_type=zstd
Formatting 'test.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zstd size=1073741824 lazy_refcounts=off refcount_bits=16
Comment 1Richard W.M. Jones
2023-08-31 13:36:30 UTC
The change to the spec file is trivial, just use:
--enable-zstd
However there is an issue that this enables zstd-compressed live migration
support, which we do not wish to support (although zlib-compressed live
migration is already enabled and unsupported).
Kevin WDYT? I am wondering that is it worth taking extra maintenance burden at this point of time. Who is planning to create and distribute zstd compressed images.
Comment 3RHEL Program Management
2023-09-22 16:29:11 UTC
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.