OK, footnotes to add then. If you have one server, and wish to flip it from VMware to Proxmox. But keep your VMs.
There is no 'totally painless' solution. You either have to move large (VMDK) files around. and-or buy some more disk(s). And-or-both really.
Safest path would be
(a) use a laptop or PC in LAN as a holding tank, bring over copies of VMDK files on an overnight copy run. Clearly you need enough local disk to hold the VMDKs
OR
(a2) attach USB drive to VMware, copy VMDK files over to that. For that matter I don't even know if vmware lets you do something as barbaric as this. You would need to read forums elsewhere if you can temporarily spin up a local storage on ESX node using a local USB drive. Or maybe you attach a direct-attach (SATA, etc) connection, configure the new storage, move the VMDKs over that way. But you want ultimately these VMs to be accessible from linux/proxmox so - probably don't want to go this route anyhow.
don't destroy your ESX host. In case things go badly. Remove-and-replace hard drives
install new drive(s)
clean install proxmox
copy in VMDK files
setup new VMs in proxmox to mimic what you want
manually copy-move VMDK files into place on proxmox / CLI under-the-hood work.
Only risk with this, is that your VMs may still give you issues. ie, it is good to have either a 'safe roll back' method, or a way to test in advance that does not involve destroying your ESX/VMWare host (or at least those disks). Or you accept your VMs will be re-deployed.
So. You have many options, the hard part will be deciding which path is preferred for you in terms of
- costs of time
- costs of money
- costs of risks (ie, loss of VM/data)
these 3 different costs are all somewhat balanced/trade-offs you can make. depending on your preferred 'budget'
As a side point / for reference. Once upon a time, years ago / before proxmox supported VMDK. I did a 'bare metal' style migration of a VMWare guest,
-- used clonezilla LiveCD to make a backup of the VM content / of the VM on ESX host.
-- send the disk image over to a local storage tank (Network SMB storage target)
-- then deploy on new proxmox host an empty VM of suitable size/resources.
-- live CD Boot clonezilla in this new proxmox host.
-- do a standard cloenzilla restore of the 'Bare metal backup" (ie, the VMware VM I wanted to migrate)
-- this worked perfectly smoothly.
Good luck with the project!
Tim