[scottjg]

i don't know what the penetration of it looks like, but on the vsphere/esxi side there are also a number of really expensive addon features that i have not seen reproduced in open source software.

1. vmotion + storage vmotion - you can live migrate a vm from one hypervisor host machine to another. you can also live migrate the underlying storage (good if you want to consolidate storage servers, rebalance disk load, etc). with some caveats, you can do all of this without any downtime in the vm. it's not just a simple suspend on one host, resume on another host. a memory snapshot is migrated while the vm is still running on the first host, and when the amount of dirty pages starts to converge, they flip the vm over to the new host. similar idea for storage vmotion.

2. fault tolerance - for single cpu vms, you can use vmware's record-replay technology to execute a secondary vm in a "shadow" mode which replicates all of the nondeterministic events across the network. if one hypervisor host dies, the other can take over with no downtime. this is great when you need to add HA for a legacy application.

3. vsan - generally you run these systems with some sort of shared storage (nfs or iscsi attached SAN, or something like that). a SAN can be really expensive and a single point of failure. vmware can create a "virtual san" from a cluster of your esxi hypervisor hosts. as you can imagine, it has all sorts of HA features and can rebalance workloads to improve performance.

there are more, but that's just a few interesting features.

[katbyte]

Fair bit of that can be done with Proxmox now. What esxi has going for it from what I hear is the ability to deal with 100/1000s of hosts over many many nodes and Proxmox struggles with that

[edwintorok]

Memory and storage live migration across hosts and pools is possible with Xen too.

See VM.pool_migrate and VM.migrate_send https://xapi-project.github.io/xen-api/classes/vm.html. Those features got introduced in Xenserver 4.0 (2007) and 6.1 (2012).

Disclaimer: I work at XenServer.

[lima]

QEMU/libvirt can live migrate VMs without downtime. It works the same way.

[everfrustrated]

VMware was doing live migration since 2002. Open source reimplantations are relatively recent.

[erkkie]

Yep, happily using https://ganeti.org/ and KVM live migrations - mirrors across hosts.

[redundantly]

> vsan... a SAN can be really expensive and a single point of failure.

In every scenario that we spec'd out vSAN for production use it came in at least two times as expensive as your average dual controller, HA capable, storage array.

vSAN pricing is absolute nonsense.

[mgiampapa]

vSAN pricing is all about what the sales guy is willing to do to make the rest of the sale. It has zero marginal cost if they can get you on the platform and using their ecosystem of tools and software.

In edge deployments where rack space is tight it's actually a great solution if you only have a few U to work with and have a HA requirement for a legacy app as well.

[ikidd]

You might be surprised how much of this the free Proxmox, running Qemu on Debian, can do.

[barkingcat]

good mention of the replay feature! I haven't used that before, but that sounds like something that they could sell for a lot of money and companies would want to buy that feature.