Abstract: Storing recovery data includes providing chunks of data to a remote destination, where each chunk of data represents data written before a first time and after a second time and where the second time for one of the particular chunks corresponds to a first time for a subsequent one of the particular chunks, providing synchronous data to a local destination, and providing an indicator to the local destination in connection with creation of a new chunk of data for storage at the remote destination. The local destination may maintain a plurality of maps, where each of the maps associates synchronous data being provided thereto with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the local destination may point to a new map. There may be two maps or more than two maps.

Abstract: Storing recovery data includes providing chunks of data to a remote destination, where each chunk of data represents data written before a first time and after a second time and where the second time for one of the particular chunks corresponds to a first time for a subsequent one of the particular chunks, providing synchronous data to a local destination, and providing an indicator to the local destination in connection with creation of a new chunk of data for storage at the remote destination. The local destination may maintain a plurality of maps, where each of the maps associates synchronous data being provided thereto with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the local destination may point to a new map. There may be two maps or more than two maps.

Abstract: A method, system, and computer program product for ordering a plurality of data IO captured at a primary site to be applied at a secondary site, comprising removing the one or more extent level portions from the captured data IO, determining if the one or more extent level portions are time sequenced to overwrite a portion of data of the data IO, based on a determination that the portion data is to be overwritten, removing the overwritten portion of data from the plurality of the data IO and ordering the one or more extent level portions to be applied at the secondary site before the captured data IO.

Abstract: A computer-implemented method of ordering data writes includes at least some of a plurality of primary storage devices receiving a first plurality of data writes and causing a cycle switch for the plurality of primary storage devices. The first plurality of data writes are associated with a particular cycle on each primary storage device in the plurality of primary storage devices. At least some of the plurality of primary storage devices receive a second plurality of writes after initiating the cycle switch. All of the second plurality of writes are associated with a cycle different from the particular cycle on each of the plurality of primary storage devices.

Abstract: Maintaining an ordering of transmitted data includes associating a sequence number with each element of the transmitted data, where the sequence number indicates a temporal relationship between different ones of the elements. Maintaining an ordering also includes maintaining a last aborted sequence number and an indicator of whether receipt of information indicating that the last aborted sequence number has been acknowledged and rejecting data associated with a sequence number indicative of a time before a time corresponding to the last aborted sequence number. The last aborted sequence number may be sent until receipt thereof is acknowledged. No data may be transmitted until receipt of the last aborted sequence number is acknowledged. The sequence numbers may be incremented by one.

Abstract: Managing data transferred from a local storage device to a remote storage device includes maintaining the data in chunks in cache memory, where data writes to the local storage device begun during a particular time interval are associated with a chunk of data that is separate from other chunks of data and where data is transferred from the local storage device to the remote storage device by transferring a particular chunk after all data writes associated with the particular chunk have completed and after a previous chunk has been acknowledged as being received by the remote storage device and, in response to use of the cache memory exceeding a first threshold, storing data from a first chunk of the cache memory to a local disk. Data writes to the local storage device may be provided by a host coupled to the local storage device.

Abstract: Storing recovery data includes providing chunks of data to a remote destination, where each chunk of data represents data written before a first time and after a second time and where the second time for one of the particular chunks corresponds to a first time for a subsequent one of the particular chunks, providing synchronous data to a local destination, and providing an indicator to the local destination in connection with creation of a new chunk of data for storage at the remote destination. The local destination may maintain a plurality of maps, where each of the maps associates synchronous data being provided thereto with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the local destination may point to a new map. There may be two maps or more than two maps.

Abstract: Storing recovery data includes providing chunks of data to a remote destination, where each chunk of data represents data written before a first time and after a second time and where the second time for one of the particular chunks corresponds to a first time for a subsequent one of the particular chunks, providing synchronous data to a local destination, and providing an indicator to the local destination in connection with creation of a new chunk of data for storage at the remote destination. The local destination may maintain a plurality of maps, where each of the maps associates synchronous data being provided thereto with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the local destination may point to a new map. There may be two maps or more than two maps.

Abstract: Storing recovery data for a data center includes providing synchronous data from the data center to a local destination, providing chunks of data from the local destination to a first remote destination, different from the first remote destination, and providing chunks of data from the data center to a second remote destination. At least some of the destinations may maintain a plurality of maps, where each of the maps associates synchronous data being provided to the local destination with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the at least some of the destinations that maintain a plurality of maps may point to a new map. There may be two maps or more than two maps.

Abstract: Toggling between a first storage configuration and a second storage configuration includes disabling asynchronous data transfer to a third storage group from one of the first storage group and the second storage group and enabling asynchronous data transfer to the third storage group from an other one of the first storage group and second storage group. Toggling between a first storage configuration and a second storage configuration may also include, prior to disabling asynchronous data transfer to the third storage group, transferring pending data to the third storage group. Toggling between a first storage configuration and a second storage configuration may also include, after enabling asynchronous data transfer to the third storage group, transferring data to the third storage group that had been pending prior to disabling asynchronous data transfer to the third storage group.

Abstract: Providing storage configurations for a data center includes providing synchronous data transfer from the data center to a local destination, establishing a first connection between the data center and a remote destination to provide chunks of data from the data center to a remote destination, establishing a second connection between the local destination and the remote destination to provide chunks of data from the local destination to the remote destination, and enabling at least one of the first and second connections to transfer chunks of data to the remote destination.

Abstract: Handling failure of a primary group at a first data center may be simulated by cloning the at least one storage volume at a second data center, cloning at least one storage volume at a third data center, cloning at least one of: buffers used for providing data to the asynchronous backup group and maps used to maintain a record of data sent to the synchronous backup group but not yet sent to the asynchronous backup group; and simulating resuming work at one of the second data center and the third data center using at least one of clones of the buffers and clones of the maps.

Abstract: Storing recovery data for a data center includes providing synchronous data from the data center to a local destination, providing chunks of data from the local destination to a first remote destination, different from the first remote destination, and providing chunks of data from the data center to a second remote destination. At least some of the destinations may maintain a plurality of maps, where each of the maps associates synchronous data being provided to the local destination with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the at least some of the destinations that maintain a plurality of maps may point to a new map. There may be two maps or more than two maps.

Abstract: Toggling between a first storage configuration and a second storage configuration includes disabling asynchronous data transfer to a third storage group from one of the first storage group and the second storage group and enabling asynchronous data transfer to the third storage group from an other one of the first storage group and second storage group. Toggling between a first storage configuration and a second storage configuration may also include, prior to disabling asynchronous data transfer to the third storage group, transferring pending data to the third storage group. Toggling between a first storage configuration and a second storage configuration may also include, after enabling asynchronous data transfer to the third storage group, transferring data to the third storage group that had been pending prior to disabling asynchronous data transfer to the third storage group.

Abstract: Handling ordered writes to a data storage device includes receiving a first chunk of data into slots of a cache of the data storage device and using a hash table to provide a correlation between cache slots containing data from the first chunk of data and locations of a logical storage device of the data storage device. Handling ordered writes may also include maintaining a circularly linked list of pointers to cache slots containing the first chunk of data. Handling ordered writes may also include receiving a second chunk of data into slots of the cache of the data storage device and receiving a message indicating that all data corresponding to the first chunk of data has been transferred to the data storage device. Handling ordered writes may also include, in response to receiving the message, storing data from the first chunk on to the logical storage device.

Abstract: Ordering data writes include a host computer providing a plurality of data writes to a primary storage device, the primary storage device assigning a first sequence number to data writes begun after a first time and before a second time, the primary storage device assigning a second sequence number, different from the first sequence number, to data writes begun after the second time, in response to completion of all writes assigned the first sequence number, the primary storage device transferring writes assigned the first sequence number to a secondary storage device, and, in response to the primary storage device transferring all writes assigned the first sequence number to the secondary storage device, the primary storage device sending a commit message to the secondary storage device. Ordering data writes may also include, in response to receiving a commit message from the primary storage device, the secondary storage device storing the data writes having the first sequence number.

Abstract: Using a local storage device to read desired data stored on a remote storage device that receives chunks of data from the local storage device includes, if the desired data is entirely in a cache of the local storage device, the local storage device returning the data from the cache and, if the desired data is not entirely in a cache of the local storage device, reading data from the remote storage device to the local storage device and the local storage device merging the data from the remote storage device with data from the local storage device at the local storage device. Using a local storage device to read desired data stored on a remote storage device that receives chunks of data from the local storage device may also include, prior to reading data from the remote storage device to the local storage device, creating a temporary storage area at the local storage device if there is data from the local storage device that is to be read. The temporary storage area may be a scratch slot.

Abstract: Transitioning from a first data transfer mode to a second data transfer mode that is different from the first data transfer mode includes a primary storage device transitioning to the second data transfer mode by first transferring writes associated with a first chunk of data to a secondary storage device after completion of all writes associated with the first chunk of data and then, after all writes associated with the first chunk of data have been transferred to the secondary storage device, transferring writes associated with a second chunk of data to the secondary storage device using the first data transfer mode. Writes begun after initiating transitioning are provided to the secondary storage device using the second data transfer mode.

Abstract: Ordering data writes include a host computer providing a plurality of data writes to a primary storage device, the primary storage device assigning a first sequence number to data writes begun after a first time and before a second time, the primary storage device assigning a second sequence number, different from the first sequence number, to data writes begun after the second time, in response to completion of all writes assigned the first sequence number, the primary storage device transferring writes assigned the first sequence number to a secondary storage device, and, in response to the primary storage device transferring all writes assigned the first sequence number to the secondary storage device, the primary storage device sending a commit message to the secondary storage device. Ordering data writes may also include, in response to receiving a commit message from the primary storage device, the secondary storage device storing the data writes having the first sequence number.

Abstract: Handling ordered writes to a data storage device includes receiving a first chunk of data into slots of a cache of the data storage device and using a hash table to provide a correlation between cache slots containing data from the first chunk of data and locations of a logical storage device of the data storage device. Handling ordered writes may also include maintaining a circularly linked list of pointers to cache slots containing the first chunk of data. Handling ordered writes may also include receiving a second chunk of data into slots of the cache of the data storage device and receiving a message indicating that all data corresponding to the first chunk of data has been transferred to the data storage device. Handling ordered writes may also include, in response to receiving the message, storing data from the first chunk on to the logical storage device.