Can you expand on what you want. I am a bit confused.
The virtual disk will always be a vmdk file stored on VMFS or NFS. You can create partitions within a virtual disk just like a real one.
Expand on what you want and hopefully we will be able to find a solution for you.
Workstation allows installing VM on a partition. I am thinking of if there has something simliar in ESXi 5?
If you have multiple RAID controllers you could present one of them to your VM using DirectPath. DirectPath allows you to present hardware directly to your VMs. This isn't the same as workstation, but similiar results.
I wouldn't recommended it unless you have a very good reason for it through. I haven't used DirectPath outside of labs, but there are plenty of whitepapers/blogs on the subject.
Welcome to the Community,
ESXi stores it's virtual machine files on "datastores" (partitions formatted with VMware's VMFS file system) on logical drives or LUNs **, depending on whether you use local or shared storage. With multiple datastores you can place the virtual disks of your VM's on the same or different datastores.
**) Only one datastore per logical disk or LUN is supported!
André
Thanks for the previous replies. Is there any format other than VMFS that ESXi 5 would support? Looks like ESXi only uses files to layout VM. From installing wizard, I cannot find options that allows installing VM on a raw partition.
If you are using shared storage you can map a raw LUN to a VM as a raw device map (RDM) in the VM's properties. Although RDMs are only supported on shared LUNs you can find tweaks on the Internet which describe how to map local drives (see e.g. http://www.vm-help.com/esx40i/SATA_RDMs.php)
André