NMC's rotating partitioned dataset scheme

"It may happen that one program is reading the file that a second program is simultaneously rewriting. This is known as a race condition, because the results depend upon which program wins the race. In IBM's Operating System (OS) there are techniques for preventing interference among programs running on the same machine. However, IBM's Asymmetric Multiprocessing System (ASP) has no provision whatsoever for preventing interference among programs running on different machines in the same system. The rotating partitioned dataset scheme solves the interference problem in the case where there is only one program at a time which rewrites files. It also solves the problem of avoiding compressing the partitioned dataset (PDS) when it runs out of space. The scheme described below could have been implemented using several datasets instead of one PDS by modifying the disk volume table of contents (VTOC) instead of the PDS directory. However, it was felt safer to leave the VTOC alone"--Introduction Peter Chase. "June 1977." "This is an unreviewed manuscript, primarily intended for informal exchange of information among NMC staff members." System requirements: Adobe Acrobat Reader. 1977 NWS (National Weather Service) Library Public Domain 1931