I was looking through the VMware website and stumbled on the free version of ESX (since 28 Jul 08). So I thought I do a test drive together with some of the very old VM Server images.
Put in a request to the data centre and they gave me a Compaq DL 360 G1 server. After rustling up the usual KVM stuff, pop in the CD and it gave me an error. Why? It seems that the free version of ESX, ESXi supports mostly HP’s G5 servers. Presumably to cut down on the size and workload. Sigh. Back to the data centre folks.
Unfortunately, they don’t have a G5 server to spare, so no test drive for now.
Looking through the specs of ESXi, it appears that the Linux service console is not available. The service console is for installing agents for server monitoring or backup. Without it you cannot use backup software or SSH to take a copy of the guest OS files. The only method available is to use the VMConverter.
Personally, I would sacrifice some performance for manageability and backup. Install VMware Server on top of Linux. Centos distribution recommended. This setup will give you the features of ESX and a bit more.
You can have Samba running and together with a cron job, stop the guest OS to take a backup. Alternatively, you can take a snapshot and backup the snapshot.