That's the one feature of similar systems that always gets left out. I understand why: it's not a priority for "cloud native" workloads. The world, however, has work loads that are not cloud native, because that comes at a high cost, and it always will. So if you'd like a real value-add differentiator for your micro-VM platform (beyond what I believe you already have,) there you go.
Otherwise this looks pretty compelling.
Thanks
virsh migrate --live GuestName DestinationURLMy team spent 4 months on our implementation of vm memory that let us do it and its still our biggest time suck. We also were able to make assumptions like RDMA that are not available.
All that to say — as someone not working on smolVMs — I am confident smolVMs and most other OSS sandbox implementations will get live migration via hypervisor upgrades in the next 12 months.
Until then there are enterprise-y providers like that have it and great OSS options that already solve this like cloud hypervisor.
By what I assume is your definition, there are plenty of "non cloud native" workloads running on clouds that need live migration. Azure and GCP use LM behind the scenes to give the illusion of long uptime hosts. Guest VMs are moved around for host maintenance.
As does OCI, and (relatively recently) AWS. That's a lot of votes.
Use case: some legacy database VM needs to move because the host needs maintenance, the database storage (as opposed to the database software) is on a iSCSI/NFS/NVMe-oF array somewhere, and clients are just smart enough to transparently handle a brief disconnect/reconnect (which is built-in to essentially every such database connection pool stack today.)
Use case: a web app platform (node/spring/django/rails/whatever) with a bunch of cached client state needs to move because the host needs maintenance. The developers haven't done all the legwork to make the state survive restart, and they'll likely never get time needed to do that. That's essentially the same use case as previous. It's also rampant.
Use case: a long running batch process (training, etc.) needs to move because reasons, and ops can't wait for it to stop, and they can't kill it because time==money. It's doesn't matter that it takes an hour to move because big heap, as long as the previous 100 hours isn't lost.
"as in how large the heap is"
That's an undecidable moving target, so let the user worry about it. Trust them to figure out what is feasible given the capabilities of their hardware and talent. They'll do fine if you provide the mechanism. I've been shuffling live VMs between hosts for 10+ years successfully, and Qemu/KVM has been capable of it for nearly 20, never mind VMware.
"CRIU"
Dormant, and still containers. Also, it's re-solving solved problems once you're running in a VM, but with more steps.
Current status is I'm looking for more feedback. In a few weeks when Ubuntu 26.04 comes out I'm going to set up my dev/stg clusters at work with it, at the moment I've only tested it in a test cluster at home.
It works this way: It creates a snapshot of the zvol, and replicates it to the secondary machine. When that's done, it does another snapshot and does a "catch up" replication (the first replication could take hours on large volumes). Pause the VM, do a final snapshot+replication. Replicate the working RAM. Start up the VM on the new host.
My problem with microVMs was that they usually won't run docker / kubernetes, I work on apps that consist of whole kubernetes clusters and want the sandbox to contain all that.
Does your solution support running k3s for example?
Really appreciate the feedback!
I have been working on something similar but on top of firecracker, called it bhatti (https://github.com/sahil-shubham/bhatti).
I believe anyone with a spare linux box should be able to carve it into isolated programmable machines, without having to worry about provisioning them or their lifecycle.
The documentation’s still early but I have been using it for orchestrating parallel work (with deploy previews), offloading browser automation for my agents etc. An auction bought heztner server is serving me quite well :)
also, yes, shuru was (still) a wrapper over the Virtualization.framework, but it now supports Linux too (wrapper over KVM lol)
They are ext4 blocks which exist independent of sandboxes.
WSL2 runs a linux virtual machine. Need to take some time and care to wire that up, but definitely feasible.
Not useful for things it hadn't been trained on before. But now I have the core functionality in place - it's been of great help.
I'd argue that it's actually a benefit; I like that I can do several generations and compare them and pick the best result. HP, for example, used to do this with software teams, and that's how we got Rocky Mountain BASIC (AIUI the competing team was East Coast BASIC).
In computing, things are much more useful when they behave in predictable ways. Even AI, many (most?) would argue.
One can’t write anything efficient without comp-sci being forefront in your mind the entire time you are writing. Which explains exactly why everything is so slow today.
If you’re not thinking about what is computable, what is not computable, and what is easily computable as you think about the problems you are trying to solve, you are a professional novice.
You definitely don't need to study computer science just to avoid making common performance issues and in fact just studying computer science doesn't mean that you aren't going to introduce things like N+1 query issues, that's sort of thing comes from experience more than anything.
Likewise, just studying computer science does not mean that you are going to be well suited for software development in the real world.
> If you’re not thinking about what is computable, what is not computable, and what is easily computable as you think about the problems you are trying to solve, you are a professional novice.
Of course I consider all of these things but that didn't come from studying computer science in college lol.
Non-determinism is a problem that you can mitigate to some extent with a bit of effort, and is important if your AI is running without a human-in-the-loop step. If you're there prompting it though then it doesn't actually matter. If you don't get a good result just try again.
Maybe. The point is that this is all new, and looking forwards I think it's worth figuring out this stuff early.
Linux was built in the 90s. Hardware improved more than a 1000x. Linux virtual machine startup times stayed relatively the same.
Turns out we kept adding junk to the linux kernel + bootup operations.
So all I did was cut and remove unnecessary parts until it still worked.
This ended up also getting boot up times to under 1s. The kernel changes are the 10 commits I made, you can verify here: https://github.com/smol-machines/libkrunfw
There's probably more fat to cut to be honest.
smolvm is a vm with some of the properties & ergonomics of containers - it's meant as a replacement for containers.
It also has file copy from host to inside the guest: https://github.com/smol-machines/smolvm/blob/70c97930dda5a92...
smolvm is a virtual machine with the ergonomics of containers like packaging and distributing, kernel is not shared. You'd run containers inside of smolvm.
Also, smolvm runs ontop of both kvm for linux and apple's hypervisor for macOS. So it's cross platform.
It is on the roadmap, but frankly I haven't used Windows in a decade. I would love for a contributor to take that on as part of the free and open source spirit.
Sounds like it could be you? :)
I wish it could, but, like your housekeeper, I don't do Windows. ;-)
To me, it feels like it could fulfill WASM's promise of a "portable execution unit that runs instantly anywhere," but with the added benefit of keeping the existing Linux binary ecosystem intact via microVMs.
I'm curious—is this kind of use case aligned with the direction you're aiming for?
I worked in AWS previously in the container space + with firecracker. I realized the container is an unnecessary layer that slowed things down + firecracker was a technology designed for AWS org structure + usecase.
So I ended up building a hybrid taking the best of containers with the best of firecracker.
Let me know your thoughts, thanks!