摘要:
To generate backup data based on a log while a power consumption of a standby system is reduced, provided is a method for data backup in which a first computer system transmits a data update record, a second storage system of a second computer system receives and then stores the data update record, and a second computer of the second computer system generates a copy of data contained in the first computer system based on the stored data update record, the method for data backup, including: monitoring the data update record transmitted by the first computer system, and stopping, when a predetermined first condition is satisfied, the second computer; and starting, when a predetermined second condition is satisfied, the second computer, thereby generating the copy of the data contained in the first computer system based on the stored data update record.
摘要:
Database synchronization processing is completed within a reasonable time, using narrow-band network that connects a primary site to a secondary site, to reduce the running cost of a system. A primary DBMS has a transaction executing unit for reading a primary DB of a primary storage system to update data as requested in an update request, and a write unit for writing the updated data in the primary storage system. The primary storage system includes an unnecessary information removing unit for overwriting an unused area in the written data successively with one of a preset character and a preset value. The primary storage system is connected, via a network, to a second storage system which stores a copy of the primary DB. The primary storage system is connected to the network via a network device which has a data compression unit for compressing a succession of the same value.
摘要:
Database synchronization processing is completed within a reasonable length of time while employing a narrow-band network as a network that connects a primary site to a secondary site, to thereby reduce the running cost of a system. A primary DBMS (101) has a transaction executing unit (104) for reading a primary DB (119) of a primary storage system (110) to update data as requested in an update request, and a write unit (106) for writing the updated data in the primary storage system (110). The primary storage system (110) includes an unnecessary information removing unit (1400) for overwriting an unused area in the written data successively with one of a preset character and a preset value. The primary storage system (110) is connected, via a network (320), to a second storage system (120) which stores a copy of the primary DB (119). The primary storage system (110) is connected to the network (320) via a network device (140) which has a data compression unit for compressing a succession of the same value.
摘要:
A disaster recovery technology capable of achieving the high-speed FO and correctly reading the logs even if the unit of logs written in the main site is large is provided. In the disaster recovery system comprising a main site and a sub-site, when the writing in units of a log block consisting of a plurality of log records is performed in the main site and the logs are applied in the sub-site, the log blocks are read from the sub-storage to verify the consistency, and it is determined whether the reading process conflicts with the writing process through the remote copy operation when reading the logs. Then, only the log blocks in which the reading process does not conflict with the writing process as a result of the determination are applied to the database. Thereby, the logs are applied in the sub-site independently to recover the database.
摘要:
In a DR system, from the viewpoint of device cost, when search is not carried out, a physical application where log recovery is available by inexpensive DB appliance server is adopted. Further, a local mirror operation at a secondary site is not carried out. Furthermore, from the viewpoint of operation, by a log apply function unit, the tendencies of a log application and operations are monitored, and a search process is accepted according to the progress conditions of the log application. When the log application does not catch up sufficiently, the search is not accepted. Moreover, when a consistency guarantee of a secondary DB is made, not transactions in process at the moment of search instruction are undone (rolled back), but only transactions in process at the moment of a search instruction are redone (rolled forward).
摘要:
A disaster recovery technology capable of achieving the high-speed FO and correctly reading the logs even if the unit of logs written in the main site is large is provided. In the disaster recovery system comprising a main site and a sub-site, when the writing in units of a log block consisting of a plurality of log records is performed in the main site and the logs are applied in the sub-site, the log blocks are read from the sub-storage to verify the consistency, and it is determined whether the reading process conflicts with the writing process through the remote copy operation when reading the logs. Then, only the log blocks in which the reading process does not conflict with the writing process as a result of the determination are applied to the database. Thereby, the logs are applied in the sub-site independently to recover the database.
摘要:
A technology capable of preventing a problem which occurs when log writing of a preceding transaction fails while reducing waiting time of a subsequent transaction is provided. A database control method for releasing locking of data held by a transaction upon reception of a transaction completion instruction from an operation terminal or the like by a database is provided. The database includes an exclusive control module, a log output module, and a log buffer. The log output module stores a transaction completion log in the log buffer upon reception of the transaction completion instruction from the operation terminal. The exclusive control module releases locking held by the transaction upon reception of storage of the transaction completion log in the log buffer.
摘要:
To reduce operational and management costs during normal operations while recovering a database without loss and maintaining on-line performance on a site. A first system includes a primary storage system (103) that stores a DB (107) and a main computer (100) that executes a primary DBMS (101), which provides a DB. A second system includes a secondary (113) that receives from the primary storage system (103) a copy of a log, which shows update differences of the DB (107), and stores a secondary DBMS (117), and a subset (500) that recovers the secondary DB (117) according to the log that is copied from the primary storage system (103). When a failure occurs in the first system, the first system is switched to the second system. A second computer (110) that executes a second DBMS (111) is added to the second system, and the secondary DB (117) that is recovered or is being recovered in the subset (500) is taken over to the second computer (110).
摘要:
A technology for verifying backup data capable of synchronizing timings of checksum calculation and verifying data consistency regardless of the storing position of the data is provided. In a backup system using a data update log, a checksum of data of a backup source and a checksum of backup data are checked, thereby verifying data consistency. Data check log generation means and the like are provided so that the data update log and the data check log are transmitted in order to a secondary site. By this means, the timings of the checksum calculation are synchronized. Further, by providing data area extraction means and the like, the verification of data consistency can be performed regardless of the storing position of the data.
摘要:
A recovery of a secondary DB is executed by a log including a update difference of a primary DB, and a command is executed by adding the command to the log and analyzing the log by a secondary site. An operation command execution in the secondary site is applied to the DB having the consistency in the transaction at the same timing as a primary site or an intended timing, by transferring and executing the operation command via the log. In the case that the command is constituted by a snap shot generating instruction, a plurality of volumes of a mirror set forming a secondary storage apparatus are set to a pair state and the secondary DB is written in each of the volumes and synchronized, and the mirror set is set to a split state after the synchronization is finished, whereby a secondary DB is stored.