I need to share the same physical partition with host, so guest and host can use it at the same time. And this disk under guest must appear as local disk and have the same letter as under host. Is it possible to achieve?
This method uses a mapped network drive and is most likely the best filesystem-safe method for making the files accessible in both systems, as long as all the guest needs is file-level access to the data.
First ensure that the VMWare Tools are installed in the guest then follow the steps below while in the virtual machine.
Then within the virutal machine itself (I'm assuming Windows here) go to My Computer and map a drive to a network share.
In XP follow this guide: http://support.microsoft.com/kb/308582
In Vista & I suspect Windows 7 (pic below)
A guide to drive mapping is at http://www.vista4beginners.com/Map-Network-Drive
I believe the folder that the share gets mapped to is of this format:
This would make the drive accessible in host and virtual machines and you would be able to set it to the drive letter you like, assuming that the drive letter is > C and you have the drive letter free in the virtual machine.
Unlikely. If the OS sees a local disk, it will want to be able to access and modify its data directly at block level, which (when done by two systems at once) will break things. For example, the directory structure is cached, and if one system modifies it on disk, the other might not notice it.