Re: [Qemu-devel] [PATCH 4/6] snapshot: implemention of common API to take snapshots

[Dietmar Maurer]

> 于 2012-12-17 14:36, Dietmar Maurer 写道:
> >>    This patch is the implemention of transaction based snapshot internal
> API.
> >
> > What exactly is the advantage of using qmp transactions (as opposed to the
> pve snapshot patches)?
>    Which pve snapshot patches you referring? 

I refer to:  

https://git.proxmox.com/?p=pve-qemu-kvm.git;a=blob;f=debian/patches/internal-snapshot-async.patch;h=6c86de3a6160c58d77baa41a7774c4a80e63639e;hb=HEAD

> In group case a check should be
> done for all snapshot first, and I need to support qmp transaction interface
> which is already there, so I build an internal transaction layer below to make
> the interface unified and relative easier to add in qmp transaction.

IMHO qmp transactions are a bit clumsy and inflexible. And as you can see with 
my patches,
there is no real need for them.

> > Seems this makes it impossible to use external commands to make
> snapshots?
> >
>    what command? can you tip more about the case?

For example, nexenta storage provides an API to create snapshots. We want to use
that. Another example would be to use lvcreate to create lvm snapshots.

- Dietmar