No, the "freeze" does not cause the buffers to be written to disk.  It
wouldn't be any different than taking a point-in-time copy of the disks.

On Thu, Aug 30, 2012 at 11:11 AM, Aria Bamdad <[email protected]> wrote:

> Just curious, could this functionality be used somehow to allow for a
> **consistent** disk snapshot using flashcopy for a live Linux guest?  What
> I
> mean is that currently, we have to shutdown the guest, do the flashcopy and
> then restart the guest.  Is there a way we can tell the Linux guest to
> freeze, take a snapshot of the disks and then resume?
>
> -----Original Message-----
> From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Rob
> van der Heij
> Sent: Thursday, August 30, 2012 7:47 AM
> To: [email protected]
> Subject: Re: LGR guest quiesce
>
> On 30 August 2012 11:43, Lu GL Gao <[email protected]> wrote:
>
> Linux guest move its memory to target z/VM member during relocating. Then
> > it quiesce and resume on target z/VM.
> > How to understand "quiesce"? What state of linux when it is in quiesce
> > time? Is idling? shutdown? or something?
> >
>
> See it as "frozen while running" -  as long as Linux is actually running,
> it may change memory that z/VM already copied over, so z/VM will copy it
> again, and again...  To stop that, finally the guest is frozen for a very
> short period, not making any further changes. That gives z/VM time to copy
> the last bits and the guest then continues to run on the other side, at the
> very instruction where it was frozen before.
> Linux will observe that some time passed where it did not run, but that's
> normal in time sharing.
>
> Rob
>
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-- 
The postings on this site are my own and don’t necessarily represent
Mainline’s positions or opinions

Mark D Pace
Senior Systems Engineer
Mainline Information Systems

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