In an in-core file system, state for the file system is maintained only within the kernel's memory. The file system needs to create its own vnodes on top of lower level file systems. For each in-core vnode of the interposed file system, there will be a vnode in the interposer's file system. However, if the machine crashes and all contents of memory are lost, no permanent disk corruption would occur due to this file system's state not having been written out.