Re: General use of zstd instead of zlib compression
On Fri, Mar 14, 2025 at 13:11:00 +0100, Peter Krempa wrote:
On Fri, Mar 14, 2025 at 11:12:09 -0000, Michael Niehren wrote:
[...]
As noted above the fact that any compression algorithm is enabled
doesn't mean that compressed data will be written.
I don't see us ever wanting to enable compression for the main disk
image for performance reasons.
Said that makes likely sense to allow enabling compression for the
backup job as an option and should be relatively straightforward to do.
Actually; since this would be a new flag we could also make it use zstd
instead of the default for images libvirt creates.
Although zstd support can be compiled out of qemu so we'd have to keep
the documentation alibistic to allow both options and also wire up a
capability flag.
The more intricate bit will be wiring up XML for selecting
non-default
compression format for the image created by libvirt (otherwise
'--reuse-external' and manual creation would be needed.