[pve-devel] [PATCH] qemu-img convert : use default cache=unsafe instead writeback

[Dietmar Maurer]

> On August 1, 2016 at 9:26 AM Dominik Csapak <d.csapak at proxmox.com> wrote:
> 
> 
> On 08/01/2016 08:51 AM, Alexandre Derumier wrote:
> > Signed-off-by: Alexandre Derumier <aderumier at odiso.com>
> > ---
> >  PVE/QemuServer.pm | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> > index 7778fb8..2414fd8 100644
> > --- a/PVE/QemuServer.pm
> > +++ b/PVE/QemuServer.pm
> > @@ -5605,7 +5605,7 @@ sub qemu_img_convert {
> >  	my $dst_path = PVE::Storage::path($storecfg, $dst_volid);
> >
> >  	my $cmd = [];
> > -	push @$cmd, '/usr/bin/qemu-img', 'convert', '-t', 'writeback', '-p', '-n';
> > +	push @$cmd, '/usr/bin/qemu-img', 'convert', '-p', '-n';
> >  	push @$cmd, '-s', $snapname if($snapname && $src_format eq "qcow2");
> >  	push @$cmd, '-f', $src_format, '-O', $dst_format, $src_path;
> >  	if ($is_zero_initialized) {
> >
> 
> is this really safe?
> 
> this also impacts cloning and the "move disk" function.
> what if i clone a vm to an nfs share and immediately move the vm to 
> another host, then start it?

I guess qemu-img does a flush before closing (or flush is automatic on close?)?