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Document snapshots here as well as SO

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Ciro Santilli
2018-02-14 06:36:35 +00:00
parent de8f396429
commit 55d3288901
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README.adoc
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@@ -1578,11 +1578,66 @@ TODO: find source. Lazy now.
=== Snapshot
https://stackoverflow.com/questions/40227651/does-qemu-emulator-have-checkpoint-function/48724371#48724371
QEMU allows us to take snapshots at any time through the monitor.
You can then restore CPU, memory and disk state back at any time.
Here's how: https://stackoverflow.com/questions/40227651/does-qemu-emulator-have-checkpoint-function/48724371#48724371
qcow2 filesystems must be used for that to work.
To test it out, login into the VM, and run:
....
/count.sh
....
Then on another shell, open the monitor:
....
./runqemu
savevm my_snap_id
....
The counting continues. The, if we load the vm:
....
loadvm my_snap_id
....
the counting goes back to where we saved. This shows that CPU and memory states were reverted.
We can also verify that the disk state is also reversed. Guest:
....
echo 0 >f
....
Monitor:
....
savevm my_snap_id
....
Guest:
....
echo 1 >f
....
Monitor:
....
loadvm
....
Guest:
....
cat f
....
And the output is `0`.
== Failed action