Abstract: An advanced clock synchronization technique is adapted for use with a replication service in a data backup and recovery storage environment. The storage environment includes a plurality of source storage systems and target storage systems, wherein the source storage systems are illustratively embodied as source replication nodes. The advanced clock synchronization technique establishes a software-only, loosely-accurate global clock based on a timestamp and an associated error boundary. Notably, the timestamp and its error boundary are used as global clock information to enable synchronization (i.e., ordering of storage requests) among the source replication nodes and/or the target storage systems, thereby ensuring consistent replication of the storage requests on the target storage systems.

Abstract: A system and method enhances performance of a log adapted for use with a storage system. The log is illustratively organized into a plurality of regions, wherein each region comprises one or more entries and wherein each region is allocated to a consistency collection. As used herein, a consistency collection is defined as a set of one or more data containers among which it is desired to maintain transaction consistency, i.e., atomicity of updates of a transaction to those containers. Each entry of the region is adapted to store an update of data from a source, e.g., an application executing on the storage system. Thus, the consistency collection may comprise multiple data containers associated with one or more applications configured to maintain the atomicity of transaction updates to the collection of containers.

Abstract: Provided are a system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: A write ordering style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The write ordering style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space of the consistency group.

Abstract: A delta query technique transmits only latest changes to data of objects from a server to one or more clients in response to a client query (request) to access the object data. A global counter is maintained for all of the objects served by the server. Every time the data of an object changes, a value of the global counter increments (updates) and the updated global counter value is then assumed (“inherited”) by that object. In addition, the global counter is updated when a client issues a request to access one or more objects. If the data of the objects has changed since the last time the client accessed the objects, the server responds with the latest object data and the updated global counter value. Notably, each client maintains a local counter having a value that, upon receipt of the latest object data, is modified to reflect the updated global counter value.

Abstract: A system and method enhances performance of a log adapted for use with a storage system. The log is illustratively organized into a plurality of regions, wherein each region comprises one or more entries and wherein each region is allocated to a consistency collection. As used herein, a consistency collection is defined as a set of one or more data containers among which it is desired to maintain transaction consistency, i.e., atomicity of updates of a transaction to those containers. Each entry of the region is adapted to store an update of data from a source, e.g., an application executing on the storage system. Thus, the consistency collection may comprise multiple data containers associated with one or more applications configured to maintain the atomicity of transaction updates to the collection of containers.

Abstract: A group stamping style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The group stamping style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space, e.g., a target storage space, of the consistency group.

Abstract: A write ordering style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The write ordering style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space of the consistency group.

Abstract: An advanced clock synchronization technique is adapted for use with a replication service in a data backup and recovery storage environment. The storage environment includes a plurality of source storage systems and target storage systems, wherein the source storage systems are illustratively embodied as source replication nodes. The advanced clock synchronization technique establishes a software-only, loosely-accurate global clock based on a timestamp and an associated error boundary. Notably, the timestamp and its error boundary are used as global clock information to enable synchronization (i.e., ordering of storage requests) among the source replication nodes and/or the target storage systems, thereby ensuring consistent replication of the storage requests on the target storage systems.

Abstract: Provided are a system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: Disclosed is a method, system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: A method for copying data over a network operating in accordance with a protocol, such as the ESCON protocol, that supports a given logical address range includes establishing a logical path over the network from a primary storage system to a secondary storage system using path logical addresses within the given logical address range. A virtual path is created over the logical path to carry the data from a source storage device in a first logical subsystem of the primary storage system to a target storage device in a second logical subsystem of the secondary storage system, wherein the first and second logical subsystems have respective first and second subsystem logical addresses which are outside the given logical address range. The virtual path is used in a peer-to-peer remote copy (PPRC) operation to copy the data from the source storage device to the target storage device.

Abstract: Disclosed is a method, system, and program for caching data. Data from a device, such as a volatile memory device or non-volatile storage device, is maintained in entries in a cache. For each entry in cache, a variable indicates both a time when the cache entry was last accessed and a frequency of accesses to the cache entry. The variable is used in determining which entry to denote from cache to make room for subsequent entries.

Abstract: Disclosed is a method, system, program, and data structure for executing write operations. A first number of write operations is initiated. Performance data is gathered indicating a total time for a second number of the initiated write operations to complete. After at least one initiated write operation has completed, at least one additional write operation is initiated if a number of outstanding write operations is less than a maximum number of write operations. The maximum number of write operations is adjusted if the performance data meets at least one threshold.

Abstract: System for the storage and maintenance of data sets updates in a storage subsystem, that comprises direct access storage device(s) that serves as the main storage of the storage subsystem and on which the data sets are originally stored; a Cache memory storage device that enables fast interaction with the storage subsystem, on which a copy of the data sets is stored; a non-volatile storage device partitioned into a plurality of fixed size non-volatile memory pages.

Abstract: A method for copying data over a network operating in accordance with a protocol, such as the ESCON protocol, that supports a given logical address range includes establishing a logical path over the network from a primary storage system to a secondary storage system using path logical addresses within the given logical address range. A virtual path is created over the logical path to carry the data from a source storage device in a first logical subsystem of the primary storage system to a target storage device in a second logical subsystem of the secondary storage system, wherein the first and second logical subsystems have respective first and second subsystem logical addresses which are outside the given logical address range. The virtual path is used in a peer-to-peer remote copy (PPRC) operation to copy the data from the source storage device to the target storage device.

Abstract: Disclosed is a method, system, program, and data structure for providing a shadow copy of data storage areas in a primary site to data storage areas in a secondary site. A definition is made of storage areas in the primary site having data to be shadowed and corresponding storage areas in the secondary site to shadow data at the storage areas in the primary site. A shadow pair comprises one primary storage area and one secondary storage area that shadows data for the primary storage area in the pair. A standard data transfer interface protocol command, such as a SCSI or Fibre Channel command, is used to configure status storage areas in the secondary site to provide status information and data for each primary and secondary storage area. A write command in the standard data transfer interface protocol is then used to write status information to the status storage areas indicating status of the shadowed data at the secondary storage areas in the pairs.

Abstract: System for the storage and maintenance of data sets updates in a storage subsystem, that comprises direct an access storage device(s) that serves as the main storage of the storage subsystem and on which the data sets are originally stored; a Cache memory storage device that enables fast interaction with the storage subsystem, on which a copy of the data sets is stored; a non-volatile storage device partitioned into a plurality of fixed size non-volatile memory pages.