A method for ensuring the consistency of main store data and backup store data

摘要

Primary mass storage devices 56 are organised into groups A,B,C, and updates made to stored data therein are written to respective journals 60 for subsequent application to the mirror stores 58. The time of the latest update for each group A,B,C is stored in the master data set MDS. Updates stored and timestamped in the journals are copied into the respective backup store when their timestamp precedes the earliest of the times stored in the master data set. The invention allows data consistency to be maintained among groups of stores. The invention may be used in data recovery.