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 command is received for writing data to a first storage location. A determination is made that previously written data is stored in the first storage location. The previously written data is copied to a second storage location, in response to determining that the previously written data is stored in the first storage location. The data is written to the first storage location, in response to copying the previously written data to the second storage location.

Abstract: A plurality of data units with associated timestamps is stored in a time based file system, wherein a timestamp corresponds to a time indicated by a system clock. A time indicated by the system clock is changed while the plurality of data units is being stored. A plurality of epochs is stored in a data structure, wherein an epoch is a period of time between a starting and an ending timestamp selected from the timestamps, and wherein successive epochs have overlapping time periods. The time based file system is reverted to an earlier point in time based on the plurality of epochs stored in the data structure.

Abstract: Disclosed is a technique for data synchronization. A first identifier for a portion of data on a primary volume is determined, wherein a unique identifier is associated with each portion of data at the primary volume. A second identifier for a portion of corresponding data at a secondary volume is determined, wherein a unique identifier is associated with each portion of data at the secondary volume. The first and second identifiers are compared. When the first and second identifiers do not match, the portion of corresponding data at the secondary volume in a storage device is replaced with the portion of data at the primary volume.

Abstract: Provided are a method, system, and program for establishing copy relationships to copy source data to target data. A request is received to establish a copy relationship indicating to copy source data to target data. A determination is made as to whether the source data defined in the request comprises target data defined in a preexisting copy relationship. A determination is made as to whether base source data copied to the target data in the preexisting copy relationship also comprises the source data indicated in the request in response to determining that the source data defined in the request comprises target data in the preexisting copy relationship. A new copy relationship is defined to copy the determined base source data to the target data indicated in the request.

Abstract: A plurality of tokens corresponding to a plurality of data units written to a rewritable file system is stored, wherein an ordering relationship is maintained among the plurality of tokens, wherein the ordering relationship is such that a first token corresponding to a first data unit is of a lesser numerical value in comparison to a second token corresponding to a second data unit, and wherein the first data unit is written at an earlier point in time in comparison to the second data unit. The rewritable file system is reverted to an indicated point in time based on the ordering relationship that is maintained among the stored plurality of tokens.

Abstract: Provided are a method, system, and article of manufacture for controlling a first storage system receiving commands from a first and second managers to create a consistency group with a second storage system. Host writes are received at the first storage system, wherein the first storage system includes a first storage system primary site and a first storage system secondary site. The first storage system sends the host writes from the first storage system primary site to the first storage system secondary site. Host write operations are quiesced at the first storage system in response to a first command from a first manager. Host write operations are resumed at the first storage system in response to receiving a second command from the first manager. The first storage system receives a run command with a marker, wherein the marker indicates a cycle number to control the cycles of the first and second storage systems.

Abstract: Provided are a method, system, and article of manufacture for managing consistency groups using heterogeneous replication engines replicating data. A common linkage manager issues a prepare to create consistency group command to a first replication manager and a second replication manager, wherein the first and second replication managers issue create consistency group commands to first and second replication engines, respectively, to form a consistency group of data at a first source storage and a second source storage to copy to a first target storage and second target storage, respectively.

Abstract: An enhanced mechanism for providing data protection for variable length records utilizes high performance block storage metadata. In an embodiment, an emulated record that emulates a variable length record, such as a Count-Key-Data (CKD) record or an Extended-Count-Key-Data (ECKD) record, is generated by a Host Bus Adapter (HBA) of a mainframe system. The emulated record comprises a sequence of extended fixed-length blocks, each of which includes a data block and a footer. A confluence of the footers defines a high performance block storage metadata unit associated with the emulated record and includes a checksum that covers all data blocks and all footers of the entire emulated record. In one embodiment, the checksum is checked during transit of the emulated record between a HBA and a storage subsystem (e.g.

Abstract: An apparatus, system, and method are disclosed for efficient creation of point-in-time versions of data using differencing in a read-before-write environment. Included in an embodiment of the invention are a receive module that receives a data block sent from a primary data storage system, a read module that reads a data block from a secondary data storage device into random access memory, the data block corresponding to the data block sent from the primary data storage system, a comparison module that compares the data block sent from the primary data storage system to the data block from the secondary data storage device and creates a differencing data file, a compression module that compresses the differencing data file and to create a compressed differencing data file, and a differencing storage module stores the compressed differencing data file in a differencing storage device.

Abstract: Provided are a method, system, and program for maintaining consistency when mirroring data using different copy technologies. Update groups having updates to primary storage locations are formed using a first copy technology. The updates in the update groups are copied to secondary storage locations. Update groups having updates to primary storage locations are formed using a second copy technology, wherein the updates in the update groups are copied to secondary storage locations. Indication is made in a data structure of a time of an update in response to including the update in one of the update groups formed using the first copy technology. Indication is also made in the data structure of a time of the update group formed using the second copy technology.

Abstract: Provided are a method, system, and article of manufacture for splitting writes between a storage controller and replication engine. A splitter executing in a storage controller manages access to primary volumes. An initialization command is received to communicate with a replication engine. A replication command is received for one primary volume and the primary volume is indicated as subject to replication. A write request is received to write data to a target primary volume of the primary volumes that is indicated as subject to the replication. The data in the write request is written to the target primary volume. The data in the write request is sent to the replication engine. The replication engine executes a copy services function associated with the target primary volume to write the data to a replication engine volume.

Abstract: Provided are a method, system, and article of manufacture for a replication engine communicating with a splitter to split writes between a storage controller and replication engine. Communication is initiated with the splitter implemented in a storage controller managing access to primary volumes. A command is sent to the splitter to copy writes to one primary volume to the replication engine. Write data is received from the splitter to one of the primary volumes following the splitter receiving the command to copy the writes to the replication engine. A determination is made of a copy services function to use for the received data. The determined copy services function is invoked to transfer the received data to a secondary storage volume.

Abstract: A method is disclosed for reliably updating a data group in a read-before-write data replication environment. The method reliably updates the data group by receiving an updated data group sent from a first storage medium to a second storage medium, comparing the updated data group with a previous data group previously existing on the second storage medium and writing the updated data group to the second storage medium. The read-before-write and differencing method disclosed maintain reliability by storing multiple copies of changes made to the second storage medium during and after the write process.

Abstract: An apparatus, system, and method are disclosed for reliably updating a data group in a data replication environment. The apparatus, system, and method reliably update the data group by receiving an updated data group sent from a first storage medium to a second storage medium, comparing the updated data group with a previous data group previously existing on the second storage medium and writing the updated data group to the second storage medium. The read-before-write and differencing method disclosed maintain reliability by storing multiple copies of changes made to the second storage medium during and after the write process.

Abstract: Provided are a method, system, and article of manufacture for copying writes from primary storages to secondary storages across different networks. A failure notification is communicated, using a first network protocol, from a primary device in a first group of at least one primary device and at least one corresponding primary storage managed by the at least one primary device to a control system in response to the primary device determining that a write to the primary storage cannot be copied to a corresponding secondary storage. A failure notification is communicated, using a second network protocol, from a primary device in a second group of at least one primary device and at least one corresponding primary storage managed by the at least one primary device to the control system in response to the primary device determining that a write to the corresponding primary storage cannot be copied to a corresponding secondary storage.

Abstract: Provided are a method, system, and article of manufacture for managing the copying of writes from primary storages to secondary storages across different networks. Information is maintained on a first group of at least one primary storage, at least one primary device managing Input/Output (I/O) access to the at least one primary storage, and at least one corresponding secondary storage to which writes to the at least one primary storage are copied and a second group of at least one primary storage, at least one primary device managing Input/Output (I/O) access to the at least one primary storage, and at least one corresponding secondary storage to which writes to the at least one primary storage are copied. A failure notification is received from one of the primary devices in the first or second group of a failure to copy a write from the primary device to the secondary device.

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 may be 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: 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: 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.