Patent ID: 7640276

Claim:
A backup method of causing a secondary server having a memory including a cache area for storing a copy of a page identified in a secondary database (DB), and causing a database management system (DBMS) of a secondary site to receive a log from a primary site and apply the log to the secondary DB to generate a copy of a primary DB of the primary site, the secondary site including the secondary DB, and a secondary storage system for holding the log, which is a data update difference, and backup data, and the DBMS for updating the secondary DB based on the log executed in the secondary server and applied to the page identified in the secondary DB, the method comprising: a log reading step of reading, by a computer comprising a processor, the log received from the primary site and identifying the page, which is targeted to be updated in the secondary DB by the log; a reusability determination step of determining high reusability or low reusability of the page identified in the secondary database, wherein reusability indicates a frequency of access to the page identified in the secondary DB when the log is applied to the backup data; a log storage step of storing the log received from the primary site in a preset log storage area when the log received from the primary site corresponds to a page determined to be low in reusability, updating, after storing the log received from the primary site, the page indicated by the log in the preset log storage area, and writing the updated page to the backup data; and a cache area update step of updating the page identified in the secondary database and stored in the cache area by applying the log received from the primary site to the page identified in the secondary database and stored in the cache area when the log received from the primary site corresponds to a page determined to be high in reusability, wherein the reusability determination step comprises: determining whether there is a page targeted to be updated by the log in the cache area, wherein when there is a page targeted to be updated by the log in the cache area, the reusability is determined to be high, and wherein when there is no page targeted to be updated by the log in the cache area, the reusability determination step further comprises: calculating a total value of a volume of logs which are stored in the log storage area and which target a page identical to the page targeted to be updated by the log and a volume of the received log, wherein when the total value is larger than a preset first value, the reusability is determined to be high, and wherein when the total value is equal to or less than the preset first value, the reusability is determined to be low.