Abstract: A method, computer program product, and computer system for preparing, by a computing device, for migration of data from a source to a target. Hash values of the data may be sorted at the source. The data may be migrated from the source to the target according to how the data was sorted at the source.

Abstract: A method is used in issuing alerts for storage volumes using machine learning. A machine learning system analyzes Input/Output (I/O) data of a storage volume in a data storage system. The machine learning system is trained with sample I/O data patterns associated with the storage volume. Based on the I/O data, the machine learning system identifies atypical behavior associated with I/O data patterns of the I/O data. The method then issues an alert.

Abstract: In one aspect, IO recovery mechanisms in active/active replication for storage clusters provide, for each write IO request: determining an extent of pages to be modified; acquiring a lock by a cluster local to the request and locally persisting data; atomically creating an entry in a local journal; and sending, by the local cluster, a data write request to a peer cluster. Upon receiving acknowledgement from the peer cluster of successful transmission, the replication journal entry is cleared, the extent is unlocked, and a notification is returned to the peer. In response to a failure event at the peer cluster after persisting the data at the local cluster and creating the journal entry at the local cluster, an aspect includes sending, to the peer cluster upon recovery of the peer cluster, the journal entry with respect to an extent corresponding to a time of the failure event.

Abstract: In one aspect, extent lock resolution for storage devices includes designating one of the storage devices as a lock winner, which takes priority over another storage device over a lock. An aspect also includes receiving a replication request issued, by a host during active/active replication, determining an extent of pages to be modified by the request, locking the extent in local storage device, and executing the request at the local device. An aspect also includes sending a write request to a remote device. If the remote device is the designated lock winner, and an attempt to lock the extent is unsuccessful, the remote device waits for the lock to become available. If the remote device is not the designated lock winner, and an attempt to lock the extent is unsuccessful, the remote device rejects the write request and sends a request to the local device to resend the write request.

Abstract: An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The at least one processing device is configured to identify a storage volume to be added to a first consistency group of a first synchronous replication session between a first storage system and a second storage system in an active-active configuration, to create a second synchronous replication session for the added storage volume between the first storage system and the second storage system, and to merge the first and second synchronous replication sessions responsive to one or more designated criteria. The second synchronous replication session is illustratively configured to be fully independent of the first synchronous replication session.

Abstract: A system, computer program product, and computer-executable method for managing replication from a production site to a target site, wherein both the production site and the target site are content addressable data storage systems, the system, computer program product, and computer-executable method including processing a replication session from the production site to the target site, collecting information related to the replication session from the production site to the target site, analyzing the information to determine whether to change the processing of the replication session, upon a positive determination, modifying the processing of the replication session.

Abstract: An apparatus comprises at least one processing device configured to define a consistency group comprising a plurality of storage volumes subject to replication from a source storage system to a target storage system. In conjunction with a transition from asynchronous replication of the consistency group to synchronous replication of the consistency group, the at least one processing device completes a current asynchronous replication cycle, utilizes a current asynchronous snapshot set on the target storage system to establish an active snapshot set on the target storage system, transfers differential data of a subsequent asynchronous replication cycle to the active snapshot set on the target storage system, specifies the active snapshot set on the target storage system as a destination of the synchronous replication, and performs a data consistency check on the target storage system utilizing an additional snapshot set generated from the active snapshot set.

Abstract: In one aspect, extent lock resolution for storage devices includes designating one of the storage devices as a lock winner, which takes priority over another storage device over a lock. An aspect also includes receiving a replication request issued, by a host during active/active replication, determining an extent of pages to be modified by the request, locking the extent in local storage device, and executing the request at the local device. An aspect also includes sending a write request to a remote device. If the remote device is the designated lock winner, and an attempt to lock the extent is unsuccessful, the remote device waits for the lock to become available. If the remote device is not the designated lock winner, and an attempt to lock the extent is unsuccessful, the remote device rejects the write request and sends a request to the local device to resend the write request.

Abstract: Implementing time-to-live (TTL) license management in an active/active (A/A) replication session is provided. In one aspect, a first host is assigned as a replication session manager, and is tasked with performing A/A replication management functions. The functions include granting a TTL license to a first and second storage array, providing IO requests to the arrays during a lifespan of the TTL license, and upon determining a communication failure occurred between the arrays, selecting one of the arrays as a winner and another as a loser; suspending the TTL license to the loser; and notifying the winner to suspend replication to the loser. Another aspect includes monitoring, by a second host, a communication connection between the first and second hosts. An aspect also includes upon determining the communication connection has failed between the first second hosts, reassigning the second host as the replication session manager to take over the management functions.

Abstract: 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.

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 apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device detects a drive failure in a first storage system comprising a plurality of drives configured in accordance with a designated redundant array of independent disks (RAID) arrangement, identifies a plurality of data pages to be rebuilt in order to recover from the drive failure, retrieves hash digests of respective ones of the identified data pages, and utilizes the hash digests to request respective corresponding data pages from a second storage system. For each of one or more data pages returned by the second storage system, the processing device utilizes the returned data page as a rebuilt data page in recovering from the drive failure so as to avoid reading multiple data pages from remaining ones of the drives of the designated RAID arrangement to rebuild that data page.

Abstract: A response is provided to a request to replicate a long hash from a production system to a plurality of target systems. Replication of the long hash to each target systems is associated with a corresponding replication session. The production system comprises a processor and a memory storing a plurality of long hashes, each long hash computed based on a data packet. A replication session is established for each target system. The long hash is retrieved for one of the replication sessions and stored in a logical cache configured as part of a logical layer of a computer system and to allow other replication sessions to access the long hash stored therein. Dynamic tracking of when each of the replication sessions accesses the long hash stored in the logical cache, takes place. The long hash is cleared from the logical cache when all replication sessions have accessed it.

Abstract: An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to identify a storage volume to be migrated from a source storage system to a target storage system, and to issue one or more commands to at least one of the source storage system and a host device as part of a migration session for the storage volume. Responsive to the one or more commands, a plurality of data pages are received, with the data pages having respective hash values that are computed based at least in part on a native page size of the target storage system as specified in at least one of the one or more commands. The one or more commands illustratively comprise a plurality of read next page commands, with a given one of the read next page commands including information identifying the storage volume, the native page size of the target storage system, and the migration session.

Abstract: A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage controller is configured to monitor a differential between a storage volume of the storage system and a previous snapshot generated for that storage volume, and responsive to the monitored differential satisfying one or more specified conditions, to generate a subsequent snapshot for the storage volume. For example, monitoring the differential between the storage volume of the storage system and the previous snapshot generated for that storage volume illustratively comprises maintaining a counter indicative of an amount of data in the storage volume that has been written since generation of the previous snapshot. In such an arrangement, generating the subsequent snapshot for the storage volume responsive to the monitored differential satisfying one or more specified conditions illustratively comprises generating the subsequent snapshot responsive to the counter exceeding a specified threshold.

Abstract: In one aspect, support for hash based xcopy replication for synchronous replication is provided. An aspect includes determining, in response to an xcopy command, whether a source logical unit (LU) and a target LU are in active synchronous replication to the same target site. Upon determining that the LUs are in active synchronous replication, increasing a count of a hash handle list, obtaining a unique full hash digest, and sending the digest with volume replication pairing identifier, offset, and length to the target. Upon receiving a request from the source, searching, by the target, for local hash handles of the digest; and upon determining the local hash handles exist in the digest, incrementing, the reference counter handle list, and sending corresponding hash handles from the source site to the target.

Abstract: An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to identify a storage volume to be migrated from a source storage system to a target storage system, and for each of a plurality of logical addresses of the storage volume, to send a command requesting a content-based signature for the logical address to at least one of the source storage system and a host device and to receive the content-based signature in response to the command. Responsive to a first one of the received content-based signatures having a corresponding data page already stored in the target storage system, the processing device updates an associated reference count in place of requesting the corresponding data page. Responsive to a second one of the received content-based signatures not having a corresponding data page already stored in the target storage system, the processing device requests the corresponding data page.

Abstract: A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage controller is configured to receive a delete instruction for a storage volume, and responsive to receipt of the delete instruction, to suspend any further changes to address metadata for the storage volume, to transfer the address metadata for the storage volume to persistent storage, and to delete the storage volume while also at least temporarily maintaining its data pages. The storage controller subsequently receives an undelete instruction for the deleted storage volume, and responsive to receipt of the undelete instruction, retrieves the address metadata from persistent storage and recovers the storage volume utilizing the address metadata. An expiration timer may be started in conjunction with the deletion of the storage volume, and responsive to the undelete instruction being received after a specified expiration time of the expiration timer, the undelete instruction is rejected.

Abstract: An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to identify a storage volume to be migrated from a source storage system to a target storage system, and to issue one or more commands to at least one of the source storage system and a host device as part of a migration session for the storage volume. Responsive to the one or more commands, a plurality of data pages are received, with the data pages having respective hash values that are computed based at least in part on a native page size of the target storage system as specified in at least one of the one or more commands. The one or more commands illustratively comprise a plurality of read next page commands, with a given one of the read next page commands including information identifying the storage volume, the native page size of the target storage system, and the migration session.

Abstract: An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to detect an error relating to storage of a given data page in a first storage system, and to send a message to at least one additional storage system, the message containing a hash handle of the given data page with the hash handle having a length that is shorter than that of a corresponding hash digest of the given data page. The processing device is further configured to receive from the additional storage system responsive to the message a recovery data page identified by the additional storage system as having the same hash handle as the given data page. Separate instances of the message containing the hash handle of the given data page may be sent to each of a plurality of additional storage systems.