Re: [libvirt] [PATCH] docs: Document NVRAM behavior on transient domains
On 19.11.2014 07:22, Martin Kletzander wrote:
On Tue, Nov 18, 2014 at 05:06:34PM +0100, Michal Privoznik wrote:
> Since 1.2.8 it's possible to use OVMF on domains. Moreover, it's
> possible to have libvirt create NVRAM file per domain. Later,
> when domain is undefined, the file is removed too. However,
> things are a bit complicated when domain's transient. There's no
> undefine to transient domains. There are two options: 1) leave
> the file behind and let mgmt app remove it. 2) remove it
> automatically as domain dies.
> But, in some scenarios mgmt app may want to preserve the file,
> copy it somewhere safe, and then copy it back when the domain is
> starting again. And this wouldn't be possible with case 2). So,
> even though case 1) leaves some files behind (possibly undeleted
> for a long time), the files themselves are small (128K each). And
> data loss is worse than full disk, isn't it?
>
Just wondering, Does that mean that _if_ the management application
relies on our remote driver (has no access) and wants to manage the
file it has to create a pool type='dir' where the files are or
something similar? It can then do vol-{up,down}load or vol-delete
properly. And by default all the variable stores are by default in
the same location (/var/lib/libvirt/nvram), so one pool for that makes
perfect sense, am I right?
Yes, that's exactly how NVRAM files are to be manipulated using our
storage APIs. Just note, that the path to NVRAM store is configurable in
domain XML, so users may configure a different path to already existing
dir pool. Then, when domain's starting up, libvirt will create the NVRAM
file and copy the contents from central image into it.
> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
> ---
> docs/formatdomain.html.in | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index d4189e6..705d497 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -147,7 +147,10 @@
> started up libvirt copies so called master NVRAM store file
> defined
> in <code>qemu.conf</code>. If needed, the
<code>template</code>
> attribute can be used to per domain override map of master
> NVRAM stores
> - from the config file. <span class="since">Since
> 1.2.8</span></dd>
> + from the config file. Note, that for transient domains if the
> NVRAM file
> + has been created by libvirt it is left behind and it management
s/it management/it is management/
ACK with the typo changed.
Martin
Ah, thanks for catching that. Fixed and pushed.
Michal