On Mon, May 13, 2024 at 01:36:27 +0530, Abhiram Tilak wrote:
> The migrate-setmaxdowntime command sets the max allowed downtime during
> live-migration, but since `snapshot-create` performs qmp migration, it also
> affects the downtime during internal/external snapshot creation.
>
> Resolves: https://gitlab.com/libvirt/libvirt/-/issues/593
> Signed-off-by: Abhiram Tilak <atp.exp@gmail.com>
> ---
> This issue was a minor change, yet it has remained without any updates for
> some time.
>
>  docs/manpages/virsh.rst | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index fa038e4547..18bdae53c9 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -3717,7 +3717,8 @@ migrate-setmaxdowntime
>
>  Set maximum tolerable downtime for a domain which is being live-migrated to
>  another host.  The *downtime* is a number of milliseconds the guest is allowed
> -to be down at the end of live migration.
> +to be down at the end of live migration. This is also used to set the max
> +downtime for creating a snapshot using ``snapshot-create``.

While this is true, the usefulness of setting max downtime for snapshots
is questionable at best. Snapshots are mostly created in paused state
when this doesn't make sense at all since the VM is "down" the whole
time.

During "live" snapshots (which are not used very much as the memory
image will be unnecessarily large) this might apply, but generally local
storage is usually fast enough for this to not be a problem.

I'm not sure what this bit of documentation would provide to the user.