Checkpointing effectively executes a qemu do_savevm function call that stores everything and anything related to the VM at the current time. To my knowledge, it IS effectively a standard qemu savevm command that also has the effect of stopping the VM. You should be able to do a -loadvm to restore from the checkpoint as desired.
If all you want to do is guarantee that any disk writes that occur while qemu is running are partitioned off to a separate entity, qemu-img provides you with the snapshot facilities to do this: http://wiki.qemu.org/Documentation/CreateSnapshot Regarding how qemu actually stores the differences/images, see: http://kashyapc.fedorapeople.org/virt/lc-2012/snapshots-handout.html Tyler > So if I wanted the images to be identical at every boot, would it be > possible to combine the -snapshot flag with checkpointing? > > I guess the part I'm not familiar with is what the checkpoint stores other > than the CPU state and the memory state. Does it pull in the qcow deltas > off the base image since boot up into the snapshot or just leave them in > the qcow2 image and somehow mark them inside of the actual image? > > > On Tue, Aug 13, 2013 at 9:47 AM, <[email protected]> wrote: > >> PS, this is where the qcow extension came from... qemu copy-on-write. >> :-) >> >> > Snapshots take the image at the point of checkpointing and freeze it. >> Any >> > further writes to the image are handled using a copy-on-write >> approach. >> > >> > The state of the disk in your example should be nearly identical. The >> only >> > thing that should change is system logs and other files that are >> modified >> > on every boot. >> > >> > Tyler >> > >> >> This is probably a silly question since I don't have an in-depth >> >> knowledge >> >> of how QEMU checkpoints work, but when I create a checkpoint, is the >> >> original image changed? I know the qcow2 file is modified, but is the >> >> actual image content of the non-snapshot portion changed? >> >> >> >> In other words, if I boot up a some qcow2 file, call >> >> checkpoint_and_shutdown() and then boot up the same qcow2 file >> (without >> >> any >> >> -loadvm option) -- is the state of the disk identical between the two >> >> boots? >> >> >> >> Thanks, >> >> Paul >> >> _______________________________________________ >> >> http://www.marss86.org >> >> Marss86-Devel mailing list >> >> [email protected] >> >> https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel >> >> >> > >> > >> > >> > _______________________________________________ >> > http://www.marss86.org >> > Marss86-Devel mailing list >> > [email protected] >> > https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel >> > >> >> >> > _______________________________________________ http://www.marss86.org Marss86-Devel mailing list [email protected] https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel
