Re: [Qemu-devel] [PATCH] qcow3 - arbitrary metadata

[Jamie Lokier <jamie@shareable.org>]

Anthony Liguori wrote:
> >Does savevm snapshot the disk images too?
> 
> Yes.

Bah, annoying.

> >  I thought it was just the
> >machine state.  Does that mean non-qcow2 disks (e.g. raw files) are
> >not snapshotted but qcow2 ones are, in the same VM?
> 
> Raw files cannot be snapshotted.

I don't want to :-)

But I do want a consistent vM.  According to QEMU docs, you can savevm
if there's at least one qcow2 disk image.  Does that mean it saves
_just_ the state of that disk, or all the qcow2 disks which are
attached (e.g. C: drive, D: drive, E: drive)?

> >It's actually just the machine state I want to save.  I want to use
> >savevm to save the state of the VM before quitting, and loadvm to
> >restart.  Like suspend-to-RAM, but doesn't require the guest to
> >cooperate.  (Does suspend work anyway?)
> >  
> If you do that, you risk having your disk in an improper state.  If 
> there are any changes to the disk after you do your savevm, they will 
> not be present after you loadvm.  This could cause very subtle data 
> corruption within your file system.

The CPU is stopped before calling savevm And when restarting, the CPU
is stopped with -S first, then loadvm, then the CPU is started.

So no disk corruption - assuming QEMU doesn't keep dirty cached
sectors in its process after savevm returns.

-- Jamie