Abstract: A network component useful in tracking write activity by writing logs containing write address information is described. The tracking component may be used in networked systems employing data mirrors to record data block addresses written to a primary storage volume during the time a data mirror is unavailable. The tracking component can be available to any network originating node, and may therefore track write activity on multiple volumes. At the time a data mirror is reconstructed, the log written may be used to construct a list of block addresses pointing to locations on a primary storage volume wherein data differs from a secondary storage volume member of the mirror. The locations maybe copied from the primary to secondary storage volume to reconstruct the data mirror. The performance impact of the tracking component is minimal and a shared network resource is offered that increases fault tolerance in the event of backup device failures.

Abstract: An apparatus, system, and method are disclosed for initializing a synchronized remote database. A creation module creates a first backup table of a backup database from a schema for a primary table of a primary database. A read module reads each row from the primary table with an application server configured to manage access to the primary database by a database application. A construction module constructs a SQL command for each row of the primary table. Each SQL command inserts data of a primary table row in the first backup table. An application module applies each SQL command to the first backup table to mirror the primary table at the first backup table.

Abstract: An apparatus, system, and method are disclosed for synchronizing a remote database. A monitor module monitors an update from a database application to a primary table of a primary database. The update is communicated through an application server. The application server is configured to manage access to the primary database by the database application. A construction module constructs a SQL command in text format that is equivalent to the update. An update module applies the SQL command to a backup table of a backup database. The backup table is a logical mirror image of the primary table prior to the application of the update to the primary table. In one embodiment, a verification module verifies that the SQL command is successfully applied to the backup table.

Abstract: Disclosed are a system, a method, and a computer program product to provide for the optimization of the output transfer load balance between the peer computers transferring data to one or more storage devices. The peer computers receive, organize and transfer the data to storage devices. The data set is composed of a plurality of data transfers. After an initial division of the data transfers between the two peers, each peer will have assigned responsibility for a number of data transfers. If the one of the peer computers completes offloading transactions earlier than the other peer, then the peer that is still transferring data will employ the other peer to execute a portion of the remaining data transfers. The operation of the system is symmetrical in that either peer may assist the other peer depending upon which peer has idle time.

Abstract: Disclosed are a system, a method, and a computer program product to provide for the optimization of the output transfer load balance between the peer computers transferring data to one or more storage devices. The peer computers receive, organize and transfer the data to storage devices. The data set is composed of a plurality of data transfers. After an initial division of the data transfers between the two peers, each peer will have assigned responsibility for a number of data transfers. If the one of the peer computers completes offloading transactions earlier than the other peer, then the peer that is still transferring data will employ the other peer to execute a portion of the remaining data transfers. The operation of the system is symmetrical in that either peer may assist the other peer depending upon which peer has idle time.

Abstract: Provided are a method, system, and article of manufacture, wherein a controller receives a request from one of a plurality of hosts. The controller determines whether a primary storage control unit coupled to the controller is operational. A response is generated by accessing the primary storage control unit, in response to determining that the primary storage control unit is operational. The response is generated by accessing a secondary storage control unit, in response to determining that the primary storage control unit is not operational, wherein data is replicated synchronously from the primary storage control unit to the secondary storage control unit.

Abstract: Provided are a method, system and program for prefetching data into cache. A prefetch command is processed that indicates at least one conditional statement and at least one block to prefetch from storage to cache in response to determining that the conditional statement is satisfied.

Abstract: Disclosed are a system, a method, and a computer program product to optimize the overall latency of transferring data from peer computers to storage devices. The latency optimization occurs after a group of data is received and organized by the peer computers. The average amount of time to transfer data to each particular storage device from the peer computers is used to determine the assignment of data transfers between the peer computers. Each peer computer maintains continuously updated measurements of the average time to transfer data to each storage device. The updated transfer time measurements are based upon a moving average with adjustable weighting of past and present measurements enabling the system to adapt to changing conditions.

Abstract: Disclosed is a technique for transferring data using multiple backup components. Responsibility for a portion of data is assigned to a first backup component. When a data update for the portion of data is received at the first backup component from a primary source, the data update is mirrored to a second backup component that is not assigned responsibility for the portion of data. Also disclosed is a technique for processing data updates with a group of backup components. It is determined that a new backup component is active. Near an end of a consistent transactions set formation period, responsibility for one or more portions of data are assigned to each backup component in the group and to the new backup component. During a next consistent transactions set formation period, data updates are processed with each backup component in the group and the new backup component. Moreover, disclosed is a technique for processing data updates with a group of backup components.

Abstract: Disclosed is a technique for data synchronization. A first identifier is determined for a portion of data at a first source. A second identifier is determined for a portion of corresponding data at a second source. The first and second identifiers are compared. When the first and second identifiers do not match, the portion of corresponding data at the second source is replaced with the portion of data at the first source.

Abstract: Disclosed is a system, method, and article of manufacture for maintaining consistent copies of data between a primary site and a secondary site. One or more backup components receive backup messages from the primary site describing transactions. Transactions received from the primary site at the backup components are referred to as “inbound transactions.” The backup components associate these inbound transactions with an identifier such that all transactions associated with a certain identifier comprise all of the activity on the consistency group for a certain period of time. The backup captain periodically notifies the backup components to pause (i.e., stop receiving inbound transactions temporarily), and once all backup components indicate that they have paused, the backup components are notified to resume receiving transactions and associate the newly received transactions with a new identifier. At the same time, the backup components are sending transactions to the secondary storage devices.

Abstract: Disclosed are a system, a method, and a computer program product to efficiently create consistent transaction sets to maintain one or more copies of data at different data storage sites. All transactions sent to a primary backup appliance during a consistent transaction set creation interval are formed into a consistent transaction set by efficiently adding new transactions as they are received and removing unnecessary transfers as newer versions arrive. When the creation interval has expired, the complete consistent transaction set is transferred to a secondary backup appliance to be used to update a consistent backup copy of the primary site data. For each consistent transaction set, there will be a tree data structure (a search tree) created that contains the addressing information for all of the blocks of data in the consistent transaction set.

Abstract: Disclosed is a system, method, and article of manufacture for maintaining data integrity. A frequency for creating consistent transactions sets is negotiated. A consistent transactions set creation duration is negotiated. At an interval determined by the frequency, during the consistent transactions set creation duration, processing of a first consistent transactions set is completed, while processing of a second consistent transactions set is delayed until the end of the consistent transactions set creation duration. After the first consistent transactions set have been offloaded to secondary storage, consistent copies of data may be created.

Abstract: Disclosed is a system, method, and article of manufacture for maintaining consistent copies of data between a primary site and a secondary site.

Abstract: Disclosed is a system, method, and article of manufacture for maintaining data integrity. A frequency for creating consistent transactions sets is negotiated. A consistent transactions set creation duration is negotiated. At an interval determined by the frequency, during the consistent transactions set creation duration, processing of a first consistent transactions set is completed, while processing of a second consistent transactions set is delayed until the end of the consistent transactions set creation duration. After the first consistent transactions set have been offloaded to secondary storage, consistent copies of data may be created.