Abstract: An apparatus includes at least one processing device comprising a processor coupled to a memory, with the processing device being configured to maintain throughput statistics for at least portions of one or more asynchronous replication cycles of a replication process carried out between a first storage system and a second storage system, and to control a transition of the replication process from an asynchronous replication mode to a synchronous replication mode based at least in part on the maintained throughput statistics. The throughput statistics are illustratively updated in conjunction with each of a plurality of detected suspensions of the synchronous replication mode, and the asynchronous replication mode is reinitiated responsive to each of the detected suspensions of the synchronous replication mode. Other embodiments include methods and computer program products.

Abstract: In one aspect, adaptive replication modes in a storage system are provided. An aspect includes during an active replication session in which a first type of replication is performed at the storage system, monitoring write input/output (IO) operations, collecting data from the write IO operations, and determining, from the collected data, write IO latency. Upon determining that a threshold value has been met from the write IO latency, where the threshold value is defined for the first type of replication, an aspect includes automatically switching from the first type of replication to a second type of replication. The second type of replication is configured to compensate for operational deficiencies detected in response to the write IO latency.

Abstract: An apparatus includes a processing device comprising a processor and a memory. The processing device is configured, in conjunction with synchronous replication of a logical storage volume between first and second storage systems, to receive a synchronous write request comprising at least a portion of a data page to be written to the storage volume, to determine a source processing module associated with the data page in the first storage system, to determine at least one of a process identifier and a processor identifier of the source processing module in the first storage system, and to select a particular one of multiple links between the first and second storage systems for use with the synchronous write request based at least in part on at least one of the process identifier and the processor identifier of the source processing module. The selected link is illustratively associated with a transmit processing module.

Abstract: An apparatus is configured to identify a storage volume to be added to a consistency group for replication from a source storage system (“source”) to a target storage system (“target”), to generate a snapshot of the storage volume, to create a dummy volume on the target, to copy the snapshot to the dummy volume, and to add the storage volume to the consistency group. In conjunction with replication of the consistency group from the source to the target, a determination is made for each of a plurality of data pages of the storage volume whether or not the data page already exists in the target as part of the dummy volume. For at least one data page that already exists in the target as part of the dummy volume, a reference count is incremented in the target for that data page instead of copying that data page from the source.

Abstract: An aspect of performing flow control of IO in a synchronous replication session between a local storage and a remote storage of a storage system includes tracking an amount of time an input/output (IO) request is processed at the remote storage including an amount of time the IO request is in transmit to and from the remote storage system. The amount of time indicates a remote latency value. An aspect also includes tracking an amount of time the IO request is processed at the local storage and calculating a difference between the remote latency value and the amount of time the IO request is processed at the local storage. The difference indicates a local latency value. An aspect further includes modifying an amount of IO requests admitted at the storage system as a function of the local latency value.

Abstract: An apparatus includes a processing device comprising a processor coupled to a memory, with the processing device being configured, in conjunction with synchronous replication of at least one logical storage volume between first and second storage systems, to acquire an address lock for a set of pages of the logical storage volume starting from a particular page of the logical storage volume, to determine content-based signatures for respective pages of the set of pages, to compute an additional signature as a function of the content-based signatures, and to send the additional signature and a pointer to the particular page from the first storage system to the second storage system, so as to permit the second storage system to verify consistency of the set of pages in the second storage system relative to the set of pages in the first storage system. Such operations are repeated for other sets of pages.

Abstract: An apparatus includes a processing device comprising a processor coupled to a memory. The processing device is configured, in conjunction with synchronous replication of at least one logical storage volume between first and second storage systems, to receive a synchronous write request comprising a data page to be written to the logical storage volume, to determine a content-based signature for the data page, and to send the content-based signature from the first storage system to the second storage system. Responsive to receipt in the first storage system of an indication from the second storage system that the data page having the content-based signature is not already present in the second storage system, the processing device is further configured to send the data page from the first storage system to the second storage system. The processing device in some embodiments implements a distributed storage controller of a content addressable storage system.

Abstract: A system, computer program product, and computer-executable method of providing a layout-independent cryptographic stamp of a distributed data set from a data storage system, the system, computer program product, and computer-executable method comprising receiving a request for a cryptographic stamp of the distributed data set, creating a hash of each slice of the distributed data set, and using each hash from each slice of the distribute data set to create the cryptographic stamp of the distributed data set.

Abstract: An apparatus includes a processing device comprising a processor coupled to a memory. The processing device is configured, in conjunction with synchronous replication of at least one logical storage volume between first and second storage systems, to receive a synchronous write request comprising a data page to be written to the logical storage volume, to determine a content-based signature for the data page, and to send the content-based signature from the first storage system to the second storage system. Responsive to receipt in the first storage system of an indication from the second storage system that the data page having the content-based signature is not already present in the second storage system, the processing device is further configured to send the data page from the first storage system to the second storage system. The processing device in some embodiments implements a distributed storage controller of a content addressable storage system.

Abstract: An aspect of performing rollback of a snapshot between source and target storage systems in an asynchronous replication session in which Sr? represents a remote snapshot subject to the rollback includes suspending host input/output operations to a current source volume (Vs), determining whether a snapshot (Sr) matching the snapshot Sr? is present in the source system and, upon determining the snapshot Sr is not present in the source storage system, searching a snapshot pair (Sk, Sk?) that is closest to the remote snapshot Sr?. An aspect also includes upon determining the pair Sk, Sk? is present in existing snapsets, performing a local rollback of the Vs to Sk, and performing remote rollback including applying a difference between Sk? and Sr? to the Vs via one of a snapshot differential bitmap from the target storage system between Sk? and Sr? for the Vs, and an internal reverse direction asynchronous replication cycle.

Abstract: In one aspect, adaptive replication modes in a storage system are provided. An aspect includes during an active replication session in which a first type of replication is performed at the storage system, monitoring write input/output (IO) operations, collecting data from the write IO operations, and determining, from the collected data, write IO latency. Upon determining that a threshold value has been met from the write IO latency, where the threshold value is defined for the first type of replication, an aspect includes automatically switching from the first type of replication to a second type of replication. The second type of replication is configured to compensate for operational deficiencies detected in response to the write IO latency.

Abstract: A method is disclosed comprising: instantiating a first plurality of type-1 network sockets on a source computing system, each of the type-1 network sockets having a first queue depth; instantiating a second plurality of type-2 network sockets on the source computing system, each of the type-2 network sockets having a second queue depth that is greater than the first queue depth; transitioning the source computing system into a first state, the first state being one in which data replication messages are transmitted by the source computing system to a target computing system by using both the type-1 and type-2 network sockets; transitioning the source computing system from the first state into a second state, the second state being one in which data replication messages are transmitted by the source computing system to the target computing system by using the type-2 network sockets.

Abstract: An aspect of performing rollback of a snapshot between a source storage system and a target storage system in a synchronous replication session includes reassigning a current replication source volume to a rollback source snapshot. The rollback source snapshot is generated for a consistency group that includes a plurality of volumes. An aspect also includes performing, for one or more snapshot trees maintained for the consistency group, a differential scan between a child of the rollback source snapshot and the current replication source volume, and calculating, from results of the differential scan, a dirty tree differential. For each difference identified in the dirty tree differential, an aspect further includes calculating a corresponding volume offset, and initiating a copy command for the current replication source volume and the rollback source snapshot. The copy command is translated to a remote metadata copy request in synchronous replication data transfer.

Abstract: An aspect of performing input/output (IO) flow control in a storage system includes receiving an IO latency factor for each IO of a plurality of IOs in a workload. The IO latency factor specifies a priority level. An aspect also includes receiving a component latency factor, with respect to each of the IOs in the workload, for each component of a plurality of components in the storage system. The component latency factor indicates a degree to which the component is considered in assessing the workload. An aspect also includes applying, during processing of the workload, the IO latency factor and the component latency factor to each of the corresponding IOs; and determining an effective average latency of the plurality of IOs in the workload as a function of the applied IO latency factors and the applied component latency factors.

Abstract: A method, system and program is described for providing virtual storage domains for content addressable system. At least one tenant data storage policy is configured for at least one tenant in a storage system. A virtual storage domain is created based on the tenant data storage policy, each virtual storage domain having a unique identifier (ID). The corresponding virtual storage domain ID is tagged to a data request based on a data set policy when data belonging to a data set gets written to the storage system. A hash signature is calculated for the data taking the data content and the storage domain ID as inputs to calculate the hash signature.

Abstract: An apparatus is configured to generate a current snapshot set for a consistency group comprising a plurality of storage volumes subject to replication from a source storage system to a target storage system, to compare one or more configuration attributes of the current snapshot set to one or more configuration attributes of a previous snapshot set generated for the consistency group, to detect a change in at least one configuration attribute of the current snapshot set relative to the previous snapshot set based at least in part on the comparing, and to communicate the detected change in the configuration attribute from the source storage system to the target storage system so as to permit the target storage system to implement a corresponding configuration update for the consistency group. The generating, comparing, detecting and communicating are illustratively performed as part of an ongoing asynchronous or synchronous replication process carried out between the source and target storage systems.

Abstract: Described embodiments provide systems and methods for operating a storage system wherein an online consistent system checkpoint is generated. The checkpoint contains a point in time image of a system and is used for providing recovery of the system to a known good state. In one embodiment the checkpoint includes volume configuration data, logical volume space, a plurality of layers of metadata, and physical data storage.

Abstract: A method is provided for use in a storage system, the method comprising: receiving an I/O request at an R-node; generating a deadline for the I/O request; generating a C-node command based on the I/O request; transmitting the C-node command and the I/O request to a C-node; calculating, by the C-node, a first remaining time based on the deadline; detecting, by the C-node, whether the first remaining time meets a first threshold; when the first remaining time meets the first threshold, executing the I/O request and transmitting, from the C-node to the R-node, synchronous replication request that is associated with the C-node command; and when the first remaining time does not meet the first threshold, causing the storage system to stop performing synchronous replication and executing the C-node command.

Abstract: Example embodiments of the present invention relate to methods, systems, and computer program products for determining replicas for removal from a plurality of replicas as defined in a data retention policy. The method includes performing asynchronous replication from a source to a target according to time-based replication cycles. A retention policy then may be identified defining a number of asynchronous replication replicas to retain and a plurality of associated periods which then may be retained according to the policy.

Abstract: An apparatus includes at least one processing device comprising a processor coupled to a memory, with the processing device being configured to maintain throughput statistics for at least portions of one or more asynchronous replication cycles of a replication process carried out between a first storage system and a second storage system, and to control a transition of the replication process from an asynchronous replication mode to a synchronous replication mode based at least in part on the maintained throughput statistics. The throughput statistics are illustratively updated in conjunction with each of a plurality of detected suspensions of the synchronous replication mode, and the asynchronous replication mode is reinitiated responsive to each of the detected suspensions of the synchronous replication mode. Other embodiments include methods and computer program products.