ESXi volumes: where are they located

I've changed disks in my ESXi server and am hoping for some advice about the config I now have. After a bit of trouble with block sizes, the extra partitions I used to have (for scratch etc.) are no longer there and I'm trying to work out where the different volumes in use are physically located.

Specifically, I'm worried that it's using a ram disk for one or more of them as my memory usage with no VMs running is over 900MB of the host's 4GB.

How do I find out?

Additional info:

• ESXi (4.1u1) is now installed to a 2 GB USB stick (was on a disk before)
• 4 volumes (i.e. GUIDs in /vmfs/volumes) are available
• Sym-links map the volumes to Hypervisor[1-3] and my datastore
• … and in '/', the Hypervisor volumes are sym-linked respectively to
  • altbootbank
  • bootbank
  • store & locker (same volume)
• 'scratch' seems to have settled down to a .locker folder on the datastore I created
• My hardware is on the ESXi HCL (With the probable exception of the drives, although presumably the Dell SAS 6/iR RAID controller ESXi sees is supported),

Any help gratefully received!

Edit: config not remembered

I've just restarted the machine and it's forgotten all the VMs (the inventory has gone back to a list of "Unknown" entries, which was what happened to the VMs when I removed the old datastore). So my Scratch is not persisting, even though it looks like it's configured to be stored on disk.