Search

Although IBM offers three operating systems for use on its mainframe, Multiple Virtual Storage (MVS) is considered the workhorse. MVS is used by the majority of large corporate data centers to support batch and online production applications, and it generally supports the most stringent security requirements. Indeed, IBM has issued a statement claiming that there are no known integrity exposures in MVS. MVS has become more powerful and efficient with each new release; however, it offers only limited native features for both sign-on security (verifying the identity of potential users) and resource protection (restricting access to data and other system resources to particular users). Most MVS installations have purchased access control software to provide this additional level of security. Currently, three access control software packages dominate this market: IBM's RACF, and Computer Associates' two products, CA-ACF2 and CA-TOP SECRET.

For years, the mainstay of corporate computing has been the centralized mainframe—a behemoth caged in a climate-controlled glass house. In most cases, this mainframe is an IBM or IBM-compatible computer running the MVS operating system and operating as either a standalone system or as part of a limited, proprietary network of mainframes within the same organization. Security on these mainframe systems has improved over time, as management has come to understand its importance and as vendors have developed and marketed access control software that is both effective and easy to use. For example, most of these systems operate with one of the major access control packages (IBM's RACF or Computer Associates' CA=ACF2 or CA=Top Secret).