Tom Beretvas joined IBM in Poughkeepsie, New York in 1964, where he worked in design automation. In 1971, he joined the MVS project and managed the performance simulation work in that project. This included many aspects of MVS performance and performance prediction. Tom has continued his involvement in performance work, and was appointed a representative to the Computer Measurement and Evaluation Project of SHARE, Incorporated. In 1975, he began a temporary assignment at the Systems Support Center in Hursley, England. There he has been involved in technical aspects of MVS marketing, which includes specialized work in performance tuning, evaluation, and measurement.
Later he was sent to Europe for 4 years on assignment with the mission of fixing the then serious MVS performance issues. He visited many installations as a roving consultant identifying and fixing performance problems. Upon return to the States for about 8 years he focused on paging performance issues and became one of the authors of both MVS and VM block paging algorithms. Paging was so closely associated with disk I/O at the time, thus he turned his attention to I/O performance problems, which became the hottest issue. He formed and became chairman of the Data Storage Architecture Board, which designed the blueprint for what later became DFSMS. He spent many ears in this job.
He is a member of the ACM and the IEEE (Computer Society). Mr. Beretvas received the B.Sc. (Eng.) in electronic engineering at the University College of London in 1959. He received the M.S.E. degree at Princeton University in 1964, and the E.E. (Professional) degree at Columbia University in New York City in 1964.
Tom retired from IBM in 1992 as a "Senior Technical Staff Member" (a somewhat exalted title) after a distinguished career in which he specialized in MVS system, storage, and paging performance. During his IBM career Tom was the author of many publications and "orange books" mostly related to performance.
Tom established Beretvas Performance Consultants in 1992 as an independent firm devoted to MVS (now z/OS) performance consulting and education, primarily in the storage (DASD) performance arena. Besides consulting assignments with Fortune 500 companies he has been very active in teaching. Thus, he has conducted week-long DASD performance, capacity planning and architecture classes independently and for IBM, HDS, STK and other vendors.