Re: [pve-devel] [RFC qemu-server 6/6] template: start VM for VMA backup

[Stefan Reiter <s.reiter@proxmox.com>]

On 6/4/21 11:47 AM, Fabian Grünbichler wrote:
> since using 'vma create ..' no longer works with immutable/read-only
> base volumes.

Why that? It shouldn't matter to vma if the base is read-only? Though I 
do see that in vma.c we don't tell QEMU that it should open the block 
backend read-only...

Anyway, I do personally think that just starting a VM is also a good way 
of doing this, though as you say, for templates it would make a lot of 
sense to restrict the VM to use less resources.

> 
> first hunk drops a leftover variable from when we did the same change to
> the PBS code path.
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
> ---
> this mimics what we already did for PBS, we still might want to think
> about limiting memory for the started VM for template backups which
> can't be resumed into operation anyway..
> 
>   PVE/VZDump/QemuServer.pm | 20 ++++----------------
>   1 file changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/PVE/VZDump/QemuServer.pm b/PVE/VZDump/QemuServer.pm
> index 44b705f..9ac77c1 100644
> --- a/PVE/VZDump/QemuServer.pm
> +++ b/PVE/VZDump/QemuServer.pm
> @@ -446,7 +446,6 @@ sub archive_pbs {
>       # proxmox-backup-client can only handle raw files and block devs
>       # only use it (directly) for disk-less VMs
>       if (!$diskcount) {
> -	my @pathlist;
>   	$self->loginfo("backup contains no disks");
>   
>   	local $ENV{PBS_PASSWORD} = $password;
> @@ -621,19 +620,8 @@ sub archive_vma {
>       }
>   
>       my $diskcount = scalar(@{$task->{disks}});
> -    if (PVE::QemuConfig->is_template($self->{vmlist}->{$vmid}) || !$diskcount) {
> -	my @pathlist;
> -	foreach my $di (@{$task->{disks}}) {
> -	    if ($di->{type} eq 'block' || $di->{type} eq 'file') {
> -		push @pathlist, "$di->{qmdevice}=$di->{path}";
> -	    } else {
> -		die "implement me";
> -	    }
> -	}
> -
> -	if (!$diskcount) {
> -	    $self->loginfo("backup contains no disks");
> -	}
> +    if (!$diskcount) {
> +	$self->loginfo("backup doesn't contain any disks");

nit: I'd leave the "backup contains no disks" message the same

>   
>   	my $outcmd;
>   	if ($comp) {
> @@ -646,9 +634,9 @@ sub archive_vma {
>   
>   	my $cmd = ['/usr/bin/vma', 'create', '-v', '-c', $conffile];
>   	push @$cmd, '-c', $firewall if -e $firewall;
> -	push @$cmd, $outcmd, @pathlist;
> +	push @$cmd, $outcmd;
>   
> -	$self->loginfo("starting template backup");
> +	$self->loginfo("starting backup");
>   	$self->loginfo(join(' ', @$cmd));
>   
>   	if ($opts->{stdout}) {
>