Abstract: A system that includes a storage volume comprising a plurality of regions. The system also includes a plurality of nodes to receive transactions related to the storage volume from one or more client computers and execute the transactions. Each node is designated as an owner of one region of the plurality of regions. Each one of the plurality of nodes includes a ticket dispenser for dispensing tickets that ensure that the transactions that are actively being executed have exclusive access to a storage object identified in the transaction.

Abstract: Disclosed herein are a system, non-transitory computer-readable medium, and method for maintaining storage unit transaction logs. Storage unit transaction logs received from controllers are separated.

Abstract: Examples herein disclose an identification of a backup power structure, among various backup power structures, implemented in a storage system. In response to the identification of the backup power structure, the examples select a data loss prevention technique to implement in storing write data to the storage system. The data loss prevention technique is selected among various loss prevention techniques corresponding to the various backup power structures.

Abstract: Examples include transaction management for a multi-node cluster. Some examples include generating a request log entry at an owner node that identifies a duplicate data location, tagging the duplicate data location with a requested tag, and issuing a zero-copy request that identifies the duplicate data location. In some such examples, a service node may generate a service log entry based on the zero-copy request that identifies the duplicate data location, process the zero-copy request, and tag the duplicate data location with a serviced tag. A determination may be made as to whether at least one of the owner node and the service node have failed and based on the determination that at least one has failed, the failed node may be recovered via at least one of the requested tag and the serviced tag of the duplicate data location.

Abstract: Examples discussed herein include receiving a notification about an event occurring in a storage array. In response to receiving the notification a cache of the storage array may be frozen and the data in the cache may be flushed to a persistent storage. The data in the cache is stored in the cache prior to the event. Examples also include receiving first data in a first host write request that is received after the event from a host device, sending a write request complete signal to the host device, and flushing the first data to the persistent storage. The first data is flushed after the data in cache is flushed.

Abstract: In some examples, a storage system dynamically selects, in response to a determined type of power backup arrangement used in the storage system, from among different powerloss data protection techniques corresponding to different types of power backup arrangements, The different powerloss data protection techniques each is responsive to loss of power by saving write data according to a common format. In response to loss of power in the storage system, the selected powerloss data protection technique is used to store write data corresponding to write operations in the storage system according to the common format to a recovery storage medium. The storage system recovers from the loss of power in the storage system by using the write data according to the common format stored using the selected powerloss data protection technique.

Abstract: Techniques are described herein for managing data in a storage array. A system includes a distributing unit to distribute compressible data and uncompressible data across compression-capable drives. The system also includes a vacating unit to vacate an excess chunklet to another drive in the storage array if a new compression factor is less than a default compression factor for the storage array.

Abstract: Examples include repair of a volume while the volume is online. In some examples, a request is received to access a compressed page, wherein the compressed page includes compressed data and compression metadata, an error is identified in the compression metadata or the compressed data, and based on the error and the request, repair of the error is handled while the volume is online.

Abstract: Techniques are provided for storing data in a deduplication store. A method includes calculating a fingerprint for data stored in a client data store. The fingerprint is compared to each of a plurality of fingerprints in a deduplication store. If the data fingerprint matches one of the plurality of fingerprints in the deduplication store, the data is moved to the deduplication store, and a back reference to the data in the deduplication store is placed in the client data store.

Abstract: An example storage system may include storage media and a storage controller. The storage controller may be to establish virtual volumes, private data stores, and a deduplication data store, each being a virtual storage space of the storage media, wherein each of the private data stores is associated with one of the virtual volumes and the deduplication data store is shared among the virtual volumes. The storage controller may, in response to receiving input data that is to be stored in a given one of the virtual volumes, determine a signature for the input data and select between storing the input data in the private data store associated with the given one of the virtual volumes and storing the input data in the deduplication data store.

Abstract: Examples include a device for memory space management. Some examples include receiving, from a host, a space management request that identifies a virtual page address. The virtual page address may be associated with a compressed page that includes a compression metadata having a reference count that indicates a number of virtual pages of data in the compressed page. The virtual page table entry associated with the virtual page address in a virtual page table may be looked up. The virtual page table entry may identify the compressed page. In such examples, the virtual page table entry may be marked as invalid without updating the reference count in the compressed page. A determination may be made as to whether each virtual page table entry that identifies the compressed page is marked invalid. Based on the determination that each virtual page table entry that identifies the compressed page is invalid, a free space bitmap entry for the compressed page may be updated to indicate that the compressed page is free.

Abstract: Storage unit priority based on configuration information may be determined, for example, by a processor analyzing configuration information associated with the storage units to create a priority order associated with the storage units. The configuration information associated with each storage unit may be standardized for comparison to the configuration information associated with the other storage units. The processor may perform an action related to the storage units according to the priority order.

Abstract: Examples include a device for memory space management. Some examples include receiving, from a host, a space management request that identifies a virtual page address. The virtual page address may be associated with a compressed page that includes a compression metadata having a reference count that indicates a number of virtual pages of data in the compressed page. The virtual page table entry associated with the virtual page address in a virtual page table may be looked up. The virtual page table entry may identify the compressed page. In such examples, the virtual page table entry may be marked as invalid without updating the reference count in the compressed page. A determination may be made as to whether each virtual page table entry that identifies the compressed page is marked invalid. Based on the determination that each virtual page table entry that identifies the compressed page is invalid, a free space bitmap entry for the compressed page may be updated to indicate that the compressed page is free.

Abstract: Methods and systems for collision handling during an asynchronous replication are provided. A system includes a cache memory system comprising a number of cache memory pages. A collision detector detects when a host is attempting to overwrite a cache memory page that has not been completely replicated. A revision page tagger copies the cache memory page to a free page and tags the copied page as protected.

Abstract: Example implementations relate to determining, based on a system busy level, throughput of logical volumes. In example implementations, a system busy level may be increased in response to a determination that a latency goal associated with one of a plurality of logical volumes has not been met. A throughput for a subset of the plurality of logical volumes may be determined based on the system busy level.

Abstract: Methods and systems for managing manifests for replication are provided. A system includes a number of origination nodes forming a source array. A remote copy ticket dispenser provides a replication ticket for a transaction to be grouped with other transactions and to be replicated to a destination array. A transaction communicator sends transactions to the destination array.

Abstract: Methods and systems for managing sets of transactions for replication are provided. A system includes a number of origination nodes forming a source array. A sequence number generator generates sequence numbers based, at least in part, on a time interval during which a transaction is received. A subset manager groups transactions into subsets based, at least in part, on the sequence number.

Abstract: A failure at a first port of the controller node is detected, where the first port is initially assigned a first port identifier and is associated with a logical path through a communications fabric between the first port and a port at a host device. In response to detecting the failure, the first port identifier is assigned to a second port to cause the logical path to be associated with the second port. In response to detecting resolution of the failure, a probe identifier is assigned to the first port. Using the probe identifier, a health of network infrastructure between the first port and the host device is checked. In response to the checking, the first port identifier is assigned to the first port to cause failback of the logical path to the first port.

Abstract: In one example, a method is described herein. The method includes generating a block device presentation, the block device presentation corresponding to a snapshot to be restored. The method also includes configuring disk transport drivers on a virtual machine to make the block device presentation accessible. The method further includes receiving a disk read request for a specified logical block address. The method also further includes mapping a disk logical address to a backup object logical byte offset range. The method also further includes returning a selected data corresponding to the specified logical block address to a target storage device.

Abstract: In example implementations, unreferenced memory addresses in a segment of a storage volume may be identified. Access to the segment of the storage volume may be controlled by one of a plurality of storage volume controllers (SVCs). The plurality of SVCs may control access to respective segments of the storage volume. Indicators of the identified unreferenced memory addresses may be stored in a volatile memory in the one of the plurality of SVCs. In response to an input/output (I/O) command from a host, data may be written to one of the identified unreferenced memory addresses corresponding to one of the indicators stored in the volatile memory. After the data has been written, the one of the indicators may be deleted from the volatile memory. The one of the identified unreferenced memory addresses may not have been made available to other SVCs after being identified.