[Xen-devel] Fast checkpoints with COW VM memory

["Mike Sun" <msun@xxxxxxxxxx>]

Hi --

According to the Xen Roadmap for 2006, there was talk of copy-on-write
functionality that could be developed easily from the
save/restore/migration code to enable features such as fast
checkpoints or even VM forks.  Has there been any progress on such
work?  Our research work would be highly interested in something to
this effect, and could contribute to the effort if it's still in
progress.

Thanks,
Mike Sun

Xen Roadmap 2006
"The save/restore/relocate in Xen provides almost all we need to be
able to take copy-on-write snapshots of VM's memory, to be used for
rollback or to checkpoint long running jobs (if the guest is
communicating with other machines then the wider effect of such a
rollback must be considered). To be able to support checkpoints, we
need to extend the tools to coordinate snapshotting of virtual disks
with taking the execution state snapshot. As well as enabling such
checkpoints to be initiated from the control tools, perhaps providing
the ability to trigger them from within the guest would be useful too.
A natural progression from supporting checkpointing would be to enable
"VM forking". Rather than creating a read-only checkpoint, the VM
effectively becomes cloned, running in a different domain, writing to
a CoW snapshot of the disk."

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