Starting from ESX 4.0, the "legacy" version of VMware's bare-metal hypervisor is a real VM, with also a virtual disk (by default named esxconsole.vmdk).
Unfortunately this does not mean that is more flexible, because you cannot manage it from vSphere Client.
But there a several (unsupported) way to manage this virtual disk:
How to Move the COS (esxconsole.vmdk) in VMware ESX 4 (vSphere)
Adding a second VMDK to your ESX Service Console
How to extend the virtual disk of the Service Console
ESX fails to boot when the disk containing the datastore with esxconsole.vmdk is detected as a snapshot
Partitioning your ESX host – part II
Best Practices for vSphere (ESX 4) Service Console Partitions