公开(公告)号：DE3379754D1

公开(公告)日：1989-06-01

申请号：DE3379754

申请日：1983-05-02

Applicant: IBM

Inventor： GAWLICK DIETER ,  GRAY JAMES NICHOLAS ,  IIMURA WALLACE MITSUO ,  OBERMARCK RONALD LESTER

IPC: G06F12/00 ,  G06F7/22 ,  G06F9/44 ,  G06F9/46 ,  G06F11/14 ,  G06F11/34 ,  G06F17/30 ,  G06F11/00

Abstract: The invention provides a computing apparatus and method for maintaining a journal log 80. The computing apparatus includes volatile storage for storing a log buffer 60 and a non-volatile storage for storing a journal log 80. Non-volatile storage means 70 are provided for storing in a write-ahead data set a plurality of short data blocks. The log buffer contents are written to the write-ahead data set responsive to a process epoch occurring before the log buffer is filled. The log buffer contents are written to the journal log upon the log buffer being filled. The redoing or undoing of data base changes is made with reference to the write ahead data set only in the case of a system failure resulting in loss of log buffer data not yet written to the journal log; otherwise data base changes are redone or undone with reference to the log buffer or journal log.