What is the status of supporting live migration?

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.

▲ genxy 4 hours ago | parent | next [-]

It helps if you offer a concrete use case, as in how large the heap is, what kinda of blackout period you can handle, and whether the app can handle all of it's open connections being destroyed, etc. The more an app can handle resetting some of it's own state, the easier LM is going to be to implement. If your workload jives with CRIU https://github.com/checkpoint-restore/criu you could do this already.

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.

	▲	topspin 3 hours ago \| parent [-]
		"Azure and GCP use LM behind the scenes" 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.

▲ fqiao 4 hours ago | parent | prev [-]

Really appreciate the suggestion! By "live migration", do you mean keeping the existing files and migrate them elsewhere with the vm?

Thanks

▲ topspin 4 hours ago | parent [-]

I mean making any given VM stop on host A and appear on host B; e.g. standard Qemu/KVM:

    virsh migrate --live GuestName DestinationURL

This is feasible when network storage is available and useful when a host needs to be drained for maintenance.

	▲	sureglymop an hour ago \| parent \| next [-]
		It's also feasible without network storage, --copy-storage-all will migrate all disks too.
	▲	fqiao 3 hours ago \| parent \| prev [-]
		I see. so right now smolvm can be stopped, and then "packed" (think of it as compressed), and restart on a different host. files in the disks are preserved, but memory snapshotting is still hard tbh