Oh wow! Unexpected and cool to see this post on Hacker News! Since then we have evolved our VM infra a bit, and I've written two more posts about this.
First, we started cloning VMs using userfaultfd, which allows us to bypass the disk and let children read memory directly from parent VMs [1].
And we also moved to saving memory snapshots compressed. To keep VM boots fast, we need to decompress on the fly as VMs read from the snapshot, so we chunk up snapshots in 4kb-8kb pieces that are zstd compressed [2].
Happy to answer any questions here!
[1]: https://codesandbox.io/blog/cloning-microvms-using-userfault...
[2]: https://codesandbox.io/blog/how-we-scale-our-microvm-infrast...
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