Systems and processes are disclosed to preserve data integrity during a storage controller failure. In some examples, a storage controller of an active-active controller configuration can back-up data and corresponding cache elements to allow a surviving controller to construct a correct state of a failed controller's write cache. To accomplish this, the systems and processes can implement a relative time stamp for the cache elements that allow the backed-up data to be merged on a block-by-block basis.

One or more techniques and/or computing devices are provided for synchronous replication. For example, synchronous replication relationships are established between a first storage object (e.g., a file, a logical unit number (LUN), a consistency group, etc.), hosted by a first storage controller, and a plurality of replication storage objects hosted by other storage controllers. In this way, a write operation to the first storage object is implemented in parallel upon the first storage object and the replication storage objects in a synchronous manner, such as using a zero-copy operation to reduce overhead otherwise introduced by performing copy operations. Reconciliation is performed in response to a failure so that the first storage object and the replication storage objects comprise consistent data. Failed write operations and replication write operations are retried, while enforcing a single write semantic. Dependent write order consistency is enforced for dependent write operations, such as overlapping write operations.

Providing Quality of Service (QoS) for replicating datasets including: receiving, by a target data repository from a source data repository, a checkpoint describing one or more updates to one or more datasets stored in the source data repository and the target data repository; adding, by the target data repository, the checkpoint to a first queue for checkpoints directed to one or more volumes in the target data repository, wherein the first queue is included in a plurality of queues for the target data repository; selecting, by the target data repository, one or more queues from the plurality of queues; and servicing an operation from each of the selected one or more queues.

An SCP data mirroring system includes a chassis housing a central processing system and an SCP subsystem. The SCP subsystem includes an SCP memory system with different priority storage queues each storing a copy of data provided by the central processing system, along with an SCP communication system and an SCP data storage subsystem. During a first time period, the SCP data storage subsystem retrieves a first copy of the data from a first storage queue in the SCP memory system and transmits it via the SCP communication system and through a network for storage on first storage device(s). During a subsequent second time period, the SCP data storage system retrieves a second copy of the data from a lower priority second storage queue in the SCP memory system and transmits it via the SCP communication system and through the network for storage on second storage device(s).

A system and method for performing a dynamic rollover of source and target latency in a replication environment. One or more tables of a source data store being replicated to a target data store are parked, wherein any subsequent changes for the parked tables are not replicated to the target data store. Open transactions are identified where the parked tables affect the source and target latency, wherein the open transactions are in-progress and not completed. The source and target latency are then calculated for the identified open transactions.

Provided are a computer program product, system, and method for using mirroring cache list to demote modified tracks from cache A modified track for a primary storage stored in the cache to mirror to a secondary storage is indicated in a mirroring cache list. The mirroring cache list is processed to select modified tracks in the cache to transfer to the secondary storage that have not yet been transferred. The selected modified tracks in the cache are transferred to the secondary storage. The mirroring cache list is processed to determine modified tracks in the cache to demote from the cache.

Provided are a computer program product, system, and method for determining space to release in a target volume to which tracks from a source volume are mirrored. A copy of a source volume table for the source volume providing a state of the tracks in the source volume for a consistency group is received. Tracks received from the source volume are written to the target volume to form the consistency group of tracks in the source volume at the target volume. A determination is made of tracks available to release from the copy of the source volume table and space allocated to the determined tracks is replaced. A point-in-time copy is created of the target volume for the consistency group. Complete is returned to forming the consistency group in response to releasing the space and creating the point-in-time copy.

A first storage system is configured to participate in a replication process with a second storage system using an active-active configuration. A request for a time-to-live (TTL) grant is received in the first storage system from the second storage system. A TTL projection time maintained in the first storage system is updated as a function of a current value of the TTL projection time, a local time in the first storage system and a TTL grant value. The TTL grant with the TTL grant value is sent from the first storage system to the second storage system in response to the request. The TTL projection time maintained in the first storage system is utilized in conjunction with revocation of the TTL grant to the second storage system. The TTL projection time illustratively specifies a time after which it is guaranteed that the TTL grant sent by the first storage system to the second storage system will have expired in accordance with a TTL expiration time maintained in the second storage system.

The present disclosure generally relates to creating virtualized block storage devices whose data is replicated across isolated computing systems to lower risk of data loss even in wide-scale events, such as natural disasters. The virtualized device can include at least two volumes, each of which is implemented in a distinct computing system. Each volume can be implemented by at least two computing devices, a first of which is configured as a primary device to which reads from and writes to the volume are directed. To ensure consistency in the distributed device, a multi-tier authority service is implemented, in which a cross-computing system authority service designates a volume as having authority to accept writes to the virtualized device, and in which a second tier authority service designates a computing device as having authority to accept writes to the volume.

Data protection operations including replication operations are disclosed. Virtual machines, applications, and/or application data are replicated according to at least one strategy. The replication strategy can improve performance of the recovery operation.