Abstract: A method is provided, comprising: receiving, from a host device, a request to create a token that represents one or more data items that are stored in a first volume, the first volume being stored in a source system; estimating an I/O latency limit for the first volume; estimating a token creation time for the token; comparing the token creation time to the I/O latency limit; when the token creation time matches the I/O latency limit: creating the token, creating a snapshot pair, mapping the token to the snapshot pair, and returning the token to the host device; when the token creation time does not match the I/O latency limit: creating the token, creating a first snapshot of the first volume at the source system, mapping the first snapshot to the token, and returning the token to the host device.

Abstract: A method is provided, comprising: receiving, at a first storage array, a first request to perform an atomic write operation at a specified address in a volume; placing a read-write lock on a first instance of the volume, and executing the atomic write operation on the first instance of the volume; transmitting, to a second storage array, a second request to perform the atomic write operation on a second instance of the volume; and detecting whether an error condition is present that is associated with the second request; when the error condition is present, comparing a first data item that is stored at the specified address in the first instance of the volume with a second data item that is stored at the specified address in the second instance of the volume, and, when the first data item matches the second data item, transmitting an acknowledgment.

Abstract: Techniques for data migration may include: copying data of a source logical device of a source system to a target logical device of a target system; during said copying, receiving at the target system an I/O operation directed to a logical address of the target logical device and intercepting the I/O operation on the target system; determining, on the target system, to request from the source system a data page stored at the logical address; responsive to determining to request the data page stored, performing processing including: issuing a request to the source system for the data page stored at the logical address; and responsive to receiving said request, sending information from the source system to the target system, wherein the information includes the data page stored at the logical address and additional logical addresses of the source logical device at which the data page is stored.

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 distributed storage system comprises a first module and a second module. The first module processes read requests for an address range, to send to the second module. The first module receives an address associated with a read request for a data page stored on the second module. A method searches a table on the first module for a content-based signature of the data page based on the address and provides the data page from a first module read cache if the content-based signature is in the read cache, where content-based signatures in the table are associated with the address range.

Abstract: In one aspect, provenance-based replication includes assigning a GUID to a first snap tree of a first storage array and another GUID to a second snap tree of a second storage array. The trees are peers of each other with respect to at least one volume replicated between the arrays. For each volume in the first array that is replicated to a volume in the second array, an aspect includes assigning a volume pairing identifier common to both volumes. Upon determining data for a volume (V1) in the first array has been lost/corrupted, an aspect includes identifying the peer tree from the GUID and using the pairing ID of V1 to search the peer tree for a volume (V2) in the second array, retrieving data for V2, computing a delta between the data of V1 and the data of V2, and reconstructing the lost/corrupted data for V1 using the delta.

Abstract: Techniques for processing data include: receiving a hierarchical structure of metadata (MD) pages for a logical device; and performing processing to copy data of the logical device from a source system to a target system. The first processing includes: determining a sequence of the MD pages in accordance with a depth first traversal of the hierarchical structure; defining a cache management policy in accordance with the sequence that indicates when to load the MD pages into a cache and when to remove the MD pages from the cache; loading MD pages into, and removing MD pages from, the cache in accordance with the cache management policy; and copying data pages stored at logical addresses of the logical device in an order in which the logical addresses are accessed using MD pages stored in the cache at various points in time in accordance with the cache management policy.

Abstract: At least one processing device receives a create-token command from a host device. Responsive to receipt of the create-token command, the processing device creates the token, generates an in-memory snapshot of data in one or more logical address ranges of one or more source storage volumes, associates the in-memory snapshot with the token, and provides the token to the host device. The processing device receives a write-via token command from the host device, the write-via-token command specifying the token and one or more logical address ranges of one or more target storage volumes. Responsive to receipt of the write-via-token command, the processing device determines whether or not differential metadata of the storage system includes one or more entries for the one or more logical address ranges of the one or more source storage volumes, and controls execution of the write-via-token command based at least in part on the determination.

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 aspect includes determining a host write rate based on a number of chunks written to a storage volume during a first replication cycle and determining a target rate based on an estimated number of chunks written during a second replication cycle. The target rate is determined by dividing the number of chunks written during the second replication cycle by a recovery point objective (RPO) period. An aspect also includes transmitting chunks written during the second replication cycle at the target rate.

Abstract: An apparatus in one embodiment comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured, in a first phase of a given write operation of a data integrity test process, to associate with each of a plurality of pages of the given write operation at least one additional field having a designated signature, and in a second phase of the given write operation, to modify the signature of the additional field for each of the pages. The processing device is further configured, in a given read operation of the data integrity test process, to determine integrity of each of at least a subset of the pages based at least in part on the signature of its associated additional field. The data integrity test process may be configured to confirm consistency of the pages written by the given write operation relative to a corresponding point-in-time replica.

Abstract: Tiering data between storage media in a content aware storage system is provided. An aspect includes, for each metadata page (MP) of a plurality of MPs: storing a first copy of the MP in a high tier storage, a second copy in an intermediate tier storage, and a third copy in low tier storage. Upon determining, in response to monitoring available space in the high tier storage, usage of the high tier storage exceeds a threshold value, an aspect includes identifying a least recently used (LRU) MP, deleting the LRU MP from the high tier storage, and destaging active entries of a metadata journal for the LRU MP. An aspect further includes receiving a request to read one of the plurality of MPs and, upon determining one of the MPs is the LRU metadata page, an aspect includes reading MP from the intermediate tier storage.

Abstract: Techniques for cache management may include: receiving pages of data having page scores, wherein each of the pages of data is associated with a corresponding one of the page scores, wherein the corresponding page score associated with a page of data is determined in accordance with one or more criteria including one or more of a deduplication score, a compression score, and a neighbor score that uses a popularity metric based on deduplication related criteria of neighboring pages of data; and storing the page of data in a cache in accordance with the plurality of page scores. The cache may include buckets of pages where each bucket is associated with a different page size and all pages in the bucket are the different page size. The one or more criteria may also include an access score. The page scores may be based on multiple criteria that is weighted.

Abstract: Time addressable storage in a content addressable storage system includes providing a log volume having an index and a journal. For each snapshot, an identifier is entered in the index and a corresponding journal offset is increased. For each write transaction received for a volume, an aspect includes recording a time, address, and hash handle as entries in the journal. Upon receiving a point in time (PIT) for one of the volumes, an aspect includes identifying a most recent snapshot (S) created before the PIT, taking a snapshot (S?) of snapshot (S), identifying a journal corresponding to the snapshot (S) in the index, and reviewing entries of the identified journal up to the PIT. An aspect further includes updating the snapshot (S?) with a corresponding hash handle for each address appearing in the entries until all write transactions before the PIT are contained in the snapshot (S?).

Abstract: A method is provided, comprising: receiving, at a source system, a first copy instruction, the first copy instruction being associated with a token that represents one or more data items, the first copy instruction instructing the source system to copy the one or more data items from a first volume to a second volume; in response to the first copy instruction, retrieving one or more hash digests from a snapshot that is associated with the token, each of the one or more hash digests being associated with a different one of the one or more data items; and transmitting, to a target system, a second copy instruction that is associated with the one or more hash digests, the second copy instruction instructing the target system to copy the one or more data items to a replica of the second volume that is stored at the target system.

Abstract: A method, computer program product, and computer system for receiving, by a target sent from a source, a first hash signature associated with a page of data. It may be determined that the first hash signature exists on the target. The target may receive a second hash signature sent from the source associated with the page of data. A third hash signature may be generated at the target. It may be determined that the second hash signature matches the third hash signature indicating the page of data exists on the target. A data-less write command may be executed using the page of data existing on the target to deduplicate the page of data existing on the target.

Abstract: A method, computer program product, and computer system for invalidating, by a target, all data in a first volume. A source may scan a hash to address table for a second volume to be migrated to the first volume. Data in the second volume may be migrated to be stored in the first volume by pushing information from the hash to address table to the target.

Abstract: An apparatus includes at least one processing device, with the at least one processing device being configured, in conjunction with synchronous replication of at least one logical storage volume between first and second storage systems arranged in an active-active configuration, to create a first snapshot of the logical storage volume in the first storage system, to create a second snapshot of the logical storage volume in the second storage system, to create a third snapshot of the logical storage volume in the first storage system, to initiate an asynchronous replication cycle to transfer differential data between the first and the third snapshots in the first storage system to the second storage system, and to utilize the second snapshot and the transferred differential data to create an additional snapshot of the logical storage volume in the second storage system that is synchronized with the third snapshot in the first storage system.

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 method is used in managing an asynchronous and synchronous transmit priority mechanism. The method receives a plurality of replication requests in conjunction with a replication process, where the plurality of replication requests comprises at least one of a first replication request or a second replication request. A first storage system that comprises a plurality of storage devices is configured to participate in the replication process with a second storage system that comprises a plurality of storage devices. The method optimizes at least one second replication request to optimize processing of the plurality of replication requests.