US 6,983,295 B1
System and method for database recovery using a mirrored snapshot of an online database
Donald Ralph Hart, Irvine, Calif. (US)
Assigned to Unisys Corporation, Blue Bell, Pa. (US)
Filed on Oct. 24, 2002, as Appl. No. 10/280,717.
Int. Cl. G06F 17/30 (2006.01); G06F 12/00 (2006.01)
U.S. Cl. 707—204 3 Claims
OG exemplary drawing
 
2. In a single host server operating system under a Master Control Program (MCP) and holding an online active database means having a data disk file means (D1) which is mirrored to an auxiliary database means having an auxiliary data disk file means (D2), a method upon failure of said online active database means for Database recovery utilizing a mirrored snapshot of said online database means wherein said online database means (D1) services a plurality of User-applications, and is mirrored to an auxiliary database means (D2), said method comprising the steps of:
(a) bringing online for Application-Users, a mirrored snapshot set of files on said auxiliary data disk file means disk (D2) which replicates said data disk means (D1);
(b) utilizing a DMUTILITY REBUILD program, initiated by a QUIESCE database command, to select that portion of said data disk file means (D1) which needs to be recovered and the logical stopping point of the recovery;
(c) verifying that said auxiliary data disk file means (D2) now has all data files resident in it which were originally on said data disk means (D1) at the time of the beginning Time Stamp;
(d) storing, by said DMUTILITY program, of a QUIESCE Time Stamp in a REBUILDINFO file to indicate when said data disk means (D1) was taken off-line to enable it to transfer (REBUILD) its data to said auxiliary data disk means (D2);
(e) reading of data changes in said audit trail file (A1) to make updating changes to said auxiliary data disk means (D2);
(f) transmitting of all data from said data disk file means (D1) and audit trail images in said audit trail file (A1) onto said auxiliary data disk file means (D2);
(g) enabling said updated auxiliary data disk file means to operate as an active database.