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From Richard Gass <richardg...@gmail.com>
Subject Re: suspending machines in Tashi
Date Fri, 23 Mar 2012 14:52:51 GMT
If I remember correctly, there may have been an issue with writing to
the DFS when this code was written.  During the suspend or migrate of
a non-persistent VM, the writing of the state needed to be very fast
in order to take a snapshot of the state, and continuously sync the
new changes until the current state was in sync with what was copied
to disk.  In our case, the DFS was not a high performance filer but
just a machine with jbod attached disks.  I think Mike would be able
to give more details about this one.

RIchard


On Fri, Mar 23, 2012 at 2:23 PM, Michael Stroucken <mxs+apache@cmu.edu> wrote:
> I'm looking at improving the speed with which VMs can be suspended or
> migrated, and I'd like to make a change to streamline things.
>
> Currently, when a machine suspends, it writes its state to the local file
> system. Once the dump is complete, the state file is copied into the DFS. On
> resuming though, the state file is fed directly to qemu from the DFS.
>
> I'd like to eliminate the copy and store the state file directly into DFS.
> In my case, the DFS is a mount on a filer, provided courtesy of Netapp.
> Writing directly to the Netapp cuts out a potential failure location plus it
> provides higher performance versus the local drive.
>
> I think it is a win, but I wanted to make sure that the suspend
> functionality wasn't intentionally organized this way.
>
> Thanks,
> Michael.



-- 
Richard Gass

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