Method for recovering data in a storage system

Abstract

n one aspect of the invention, there is disclosed a recovery method in a storage system that integrates shadow page and deferred update techniques. Updates of a page in the buffer are not immediately reflected to the database, but are deferred until the transaction is committed. Instead, the updated buffer page is stored in the log volume in the unit of a page. When reading a page that does not exist in the buffer from the disk, the up-to-date page from the database or from the log volume is read. Then the log table index is used to determine whether the up-to-date page exists in the database or in the log volume and to identify the position of the page stored in the log volume if the up-to-date page exists in the log volume.