An efficient I/O interface for optical disks

Abstract

We introduce the notion of an I/O interface for optical digital (write-once) disks, which is quite different from earlier research. The purpose of an I/O interface is to allow existing operating systems and application programs that use magnetic disks to use optical disks instead, with minimal change. We define what it means for an I/O interface to be disk-efficient. We demonstrate a practical disk- efficient I/O interface and show that its I/O performance in many cases is optimum, up to a constant factor, among all disk-efficient interfaces. The interface is most effective for applications that are not update-intensive. An additional capability is a built-in history mechanism that provides software support for accessing previous versions of records. Even if not implemented, the I/O interface can be used as a programming tool to develop efficient special purpose applications for use with optical disks.