Abstract: Prioritizing highly performant storage systems for servicing a synchronously replicated dataset: detecting a communication fault between two or more storage systems that are synchronously replicating a dataset; identifying a preferred storage system for winning mediation, including determining that the preferred storage system winning mediation would result in better performance than other storage systems winning mediation; and requesting, by the preferred storage system, mediation from a mediation target.

Abstract: A storage system switching between mediation models within a storage system, where the switching between mediation models includes: determining, among one or more of the plurality of storage systems, a change in availability of a mediator service, wherein one or more of the plurality of storage systems are configured to request mediation from the mediator service in response to a fault; and communicating, among the plurality of storage systems and responsive to determining the change in availability of the mediator service, a fault response model to be used as an alternate to the mediator service among one or more of the plurality of storage systems.

Abstract: A system, method, and product for flexible RAID layouts in a storage system, including: determining a reliability of an individual storage device of a plurality of storage devices, the individual storage device containing a plurality of portions of a Redundant Array of Independent Disks (RAID) stripe in a storage system, wherein the RAID stripe includes user data and inter-device parity data; detecting a change in the reliability of the individual storage device that contains the portion corresponding to the RAID stripe; and changing an amount of intra-device protection corresponding to the RAID stripe by decreasing, in the RAID stripe, an amount of space used to store the inter-device protection data.

Abstract: Continuous data protection, including sending, to a target data repository from a source data repository, metadata describing one or more updates to one or more datasets stored within the source data repository; generating, based on the metadata describing the one or more updates to the one or more datasets, an ordered log of metadata describing an ordered application of the one or more updates to the one or more datasets; and generating, on the source data repository and based on the ordered log of metadata, the one or more datasets in accordance with the one or more updates corresponding to a specified point in time.

Abstract: Managing connectivity to synchronously replicated storage systems, including: identifying a plurality of storage systems across which a dataset is synchronously replicated; identifying a host that can issue I/O operations directed to the dataset; identifying a plurality of data communications paths between the host and the plurality of storage systems across which a dataset is synchronously replicated; identifying, from amongst the plurality of data communications paths between the host and the plurality of storage systems across which a dataset is synchronously replicated, one or more optimal paths; and issuing, to the host, an identification of the one or more optimal paths.

Abstract: Intelligent responses to errors in a storage system, including: after a first attempt to read data from a first set of resources in a storage system results in an error, determining whether to issue a second attempt to read data from the first set of resources in a storage system; responsive to determining not to issue the second attempt to read data from the first set of resources in a storage system, retrieving the data from a second set of resources in the storage system; and responsive to determining to issue the second attempt to read data from the first set of resources in a storage system, issuing a second read attempt to read the data, wherein the error correction effort level associated with the second attempt is increased relative to the error correction effort level associated with the first attempt.

Abstract: Utilizing multiple redundancy schemes within a unified storage element, including: receiving, in a storage system at a unified storage element that integrates both fast durable storage and bulk durable storage, a data storage operation from a host computer; storing, in accordance with a first data resiliency technique that corresponds to a RAID N+R format, data corresponding to the data storage operation within the fast durable storage of the unified storage element; and responsive to determining that the complete RAID stripe has been written to the fast durable storage, moving a portion of the stored data from the fast durable storage to the bulk durable storage of the unified storage element, the bulk durable storage storing the data in accordance with a second data resiliency technique that corresponds to a RAID M+R format, wherein M is different from N.

Abstract: A storage system is provided. The storage system includes a plurality of storage units, each having a controller and solid-state storage memory. The storage system further includes one or more first pathways that couple processing devices of a plurality of storage nodes and is configured to couple to a network external to the storage system and one or more second pathways that couple the plurality of storage nodes to the plurality of storage units, wherein the one or more second pathways enable multiprocessing applications.

Abstract: A system with storage memory and a processing device has a logical deletion to physical erasure time bound. The system dereferences data, responsive to a direction to delete the data. The system monitors physical blocks in storage memory for live data and the dereferenced data. The system cooperates garbage collection with monitoring the physical blocks, so that at least a physical block having the dereferenced data is garbage collected and erased within a logical deletion to physical erasure time bound.

Abstract: Creating a modifiable cloned image of a dataset, including: generating, based on a dataset stored within a source data repository, a tracking copy of replica data on a target data repository; generating, after receiving an indication to begin accepting modifications to the tracking copy of the replica data, a cloned image of the dataset that is modifiable without modifying the tracking copy of the replica data; and responsive to a storage operation directed to the target data repository, modifying the cloned image of the dataset without modifying the tracking copy of the replica data.

Abstract: Writing data in a storage system that includes a first type of storage device and a second type of storage device, including: selecting, for one or more unprocessed write requests, a target storage device type from the first type of storage device and the second type of storage device; issuing a first group of write requests to the first type of storage device, the first group of write requests addressed to one or more locations selected in dependence upon an expected address translation to be performed by the first type of storage device; and issuing a second group of write requests to the second type of storage device, the second group of write requests addressed to one or more locations selected in dependence upon a layout of memory in the second type of storage device.

Abstract: Continuing to service a dataset after prevailing in mediation, including: requesting, by a first storage system, mediation from a mediation service that is configured to resolve which storage system continues to service a dataset after the triggering event, wherein the dataset is synchronously replicated by a plurality of storage systems that includes the first storage system and a second storage system; and detaching the second storage system from a plurality of storage systems synchronously replicating the dataset.

Abstract: A method for deleting a set of keys from a storage server is provided. The method includes generating a probabilistic data structure for a first set of keys and for each key in a second set of keys, determining whether a key of the second set of keys is found in the probabilistic data structure. The method includes identifying the key as a candidate for deletion if the key is not found in the probabilistic data structure. A system is also provided.

Abstract: Utilizing different data compression algorithms based on characteristics of a storage system, including: selecting, in dependence upon a priority for conserving processing resources or storage resources in a storage system, a data compression algorithm to utilize to compress data; detecting that at least one of an amount of processing resources available in the storage system or the amount of space available to store additional data in the storage system has changed; and responsive to detecting that at least one of the amount of processing resources available in the storage system or the amount of space available to store additional data in the storage system has changed, selecting a different data compression algorithm to utilize to compress data.

Abstract: A system and method for managing tables in a storage system is described.

Abstract: Restoring lost data including detecting that a portion of the dataset stored in a first storage system has become unavailable, obtaining an identifier for the portion of the dataset, locating, using the identifier, a replacement portion of the dataset that is stored at one or more other storage systems, and writing, to the dataset that is stored in the first storage system, the replacement portion of the dataset as a replacement of the portion of the dataset that has become unavailable, where the writing occurs automatically, without user intervention.

Abstract: A method of cache management, the method comprising: identifying, among a plurality of storage items, storage items having an access count above a first threshold to generate a set of storage items; identifying, among the set of storage items, storage items having an updated access count above a second threshold to generate a subset of storage items, wherein, for each storage item, the updated access count is dependent upon a number of accesses subsequent to generating the set of storage items; and adding the storage items of the subset of storage items to a cache.

Abstract: A system and method comprising: receiving a request to write data stored at a first range of a first volume to a second range of a second volume, where first metadata for the first range of the first volume is associated with a range of physical addresses where the data is stored in the storage system; and responsive to receiving the request: creating second metadata for the second range of the second volume, wherein the second metadata is associated with the range of physical addresses where the data is stored in the storage system; and associating the second volume with the second metadata.

Abstract: A uniform model for distinct types of data replication, including receiving, at a source data repository, an update to a dataset; generating, based on the update to the dataset, both metadata describing the update to the dataset and also a metadata representation of the dataset; and initiating, based on the same metadata describing the update to the dataset and also based on the same metadata representation of the dataset, either a first type of data replication or a second type of data replication from among a plurality of types of data replication.

Abstract: Delaying deletion of a dataset, including: associating an eradication timer with the dataset, wherein the eradication timer specifies an amount of time to delay a requested deletion of the dataset; determining that the amount of time to delay the requested deletion of the dataset should be modified; and modifying the eradication timer to specify a modified amount of time to delay the requested deletion of the dataset.