Do you have write permissions to the current working directory? I don't know what err=113 means, but the guest instance needs permissions to create the file on the local file system.

From: [] On Behalf Of Pranjal Kumar Dutta
Sent: Monday, May 29, 2006 11:54 PM
Subject: [uml-user] Problems in sharing filesystems between Virtual Machines

          I am facing a problem in sharing a single root fileystem between multiple UML instances through COW (Copy on write). I am following the steps given in  for sharing fileystems between multiple UML instances.
I am using the root_fs.rh-9-full.pristine.20030724.bz2     root filesystem from .
When I start my UML instance with ./vmlinux ubd0=root_fs_cow, root_fs_sh9_pristine  devfs=nomount rw, it failes to boot up saying that can't open root_fs_cow err=113 etc. As per the steps given in the link it's not necessary to have a root_fs_cow and willl create when UML booted up fisrt time, right?