As opposed to the Xen/Sun xVM storage virtualization is done in the ESX Kernel (the simple case where no dedicated hardware storage is reserved and defined as passthrough for the virtual machine):
The ESX kernel emulates known hardware, such as a Busmaster IDE controller or some SCSI cards (Buslogic, LSILogic Parallel and LSILogic SAS). You may eliminate this hardware emulation layer by choosing "PVSCSI" (paravirtualized SCSI controller) as controller type in the VM configuration.
PVSCSI booting is not yet supported for Windows systems though, on Linux it is sufficient to include the "pvscsi" kernel module in the initial ramdisk (initrd).
The image files used to be served as virtual hard disk to guest systems are in "datastores" which are formatted with the VMFS file system, proprietary to ESX. Even the service console does not see them, but there are tools to move files in the store and to download them from the store. It is convenient to store all relevant installation ISO images in one of the defined ESX datastores so installation is simple and rapid.
PVSCSI booting is not yet supported for Windows systems though, on Linux it is sufficient to include the "pvscsi" kernel module in the initial ramdisk (initrd).
The image files used to be served as virtual hard disk to guest systems are in "datastores" which are formatted with the VMFS file system, proprietary to ESX. Even the service console does not see them, but there are tools to move files in the store and to download them from the store. It is convenient to store all relevant installation ISO images in one of the defined ESX datastores so installation is simple and rapid.
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