Emc Corporation

Emc IP Holding Company LLC

Benjamin W Yoder

Mark J Halstead

David Meiri

Deepak Vokaliga

Vadim Longinov

Douglas Eric LeCrone

Brett A Quinn

Gary H Cox

Haim Kopylovitz

Hana Moreshet

Bhaskar Bora

Marik Marshak

Adi Ofer

Svetlana Sokolova

Mike Specht

Dan Arnon

William R Stronge

Kevin C Heasley

William P Thibodeau

George Quill

Arieh Don

Alexandr Veprinsky

Peng Wu

Michael J Scharland

Rong Yu

Benoit Joseph Merlet

Assaf Natanzon

Owen Martin

Bradford B Glade

Michael E Specht

Subin George

Dale Hagglund

Kaustubh S Sahasrabudhe

Rajesh Mishra

William Alan Hatstat

Oliver M D Shorey

Dharmesh Thakkar

Eugene Ortenberg

Sandeep Chandrashekara

Kevin Loehfelm

Weiqun Li

Deepika Kini

Snapshots may be used to implement remote replication, for example, asynchronously, between a first storage system, A1, and a second storage system, A2. A1 may take a first snapshot, SS2, of a logical storage unit, R1. After the snapshot SS2it taken, any dependent write operations associated with SS2may be reconciled, and differences between SS2and the last snapshot for R1, SS1, may be determined and recorded as a difference set. One or more replication instructions for R1 that include the write operations (or data and metadata corresponding thereto) of the difference set may be sent from A1 to A2. A2 may apply the differences to R2, and then take (activate) a snapshot of R2, SS2, which is a replica of SS2. After A2 activates SS2, A2 may send an acknowledgement to A1 indicating that SS2has been activated, and A2 may take a next snapshot of R1.

Snapshot-based remote replication

Data may be replicated from a host storage system to a target storage system. It may be determined to replicate a first logical storage element on the source storage system to a second logical storage element on the target storage system, wherein the first logical storage element defines a first data portion having a first value. It may be determined that a third logical storage element on the target storage system defines a second data portion having the first value. The first logical storage element may be replicated to the second logical storage element by establishing a deduplication relationship between the second logical storage element and the third logical storage element on the target storage system without transmitting the first data portion from the source storage system to the target storage system.

Remotely replicating duplicated data

Aspects of the present disclosure relate to data cache management. In embodiments, a logical block address (LBA) bucket is established with at least one logical LBA group. Additionally, at least one LBA group is associated with two or more distinctly sized cache slots based on an input/output (IO) workload received by the storage array. Further, the association includes binding the two or more distinctly sized cache slots with at least one LBA group and mapping the bound distinctly sized cache slots in a searchable data structure. Furthermore, the searchable data structure identifies relationships between slot pointers and key metadata.

Cache memory architecture and management

Aspects of the present disclosure relate to data cache management. In embodiments, a storage array's memory is provisioned with cache memory, wherein the cache memory includes one or more sets of distinctly sized cache slots. Additionally, a logical storage volume (LSV) is established with at least one logical block address (LBA) group. Further, at least one of the LSV's LBA groups is associated with two or more distinctly sized cache slots based on an input/output (IO) workload received by the storage array.

Cache slots on a storage system may be shared between entities processing write operations for logical storage unit (LSU) tracks and entities performing remote replication for write operations for the LSU tracks. If a new write operation is received on a first storage system (S1) for a track of an LSU (R1) when the cache slot mapped to the R1 track is locked by a process currently transmitting data of the cache slot to a second storage system (S2), a new cache slot may be allocated to the R1 track, the data of the original cache slot copied to the new cache slot, and the new write operation for the R1 track initiated on S1 using the new cache slot; while the data of the original cache slot is independently, and perhaps concurrently, transmitted to S2 to be replicated in R2, the LSU on S2 that is paired with R1.

Resolving cache slot locking conflicts for remote replication

Maintaining consistency for asynchronous replication of LUNs of a local storage system to corresponding LUNs of a remote storage system includes copying application data written to LUNs to cache slots, copying metadata of LUNs to cache slots, associating a first sequence number to all metadata modifications and all application data writes that are begun after a first time and before a second time, associating a second sequence number, different from the first sequence number, to all metadata modifications and all application data writes that are begun after the second time, and, after completion of all metadata modifications and all application data writes associated with the first sequence number, initiating transfer to the remote storage system of all metadata modifications and all application data writes associated with the first sequence number. Each cache slot may include a field that indicates a corresponding sequence number.

Maintaining consistency of asynchronous replication

Peer storage systems share the workload of asynchronously replicating a shared logical storage unit (LSU) to a target system. Peer storage systems (S1 and S2) that synchronously replicate a shared LSU share the workload of asynchronously replicating the shared LSU to a target system (S3) by dividing ownership of the replication cycles in an alternating manner without a strict synchronization of cycles between the peer storage systems. Rather, a given cycle number (e.g., Cycle 1) on S1 may not start and end with a same write operation as a same cycle number (Cycle 1) on S2, such that cycles on S1 (e.g., Cycle 1 and Cycle 2) overlap with cycles having the same number (Cycle 1 and Cycle 2) on S2. S1 may asynchronously replicate to S3 only the cycles it owns, and S2 may asynchronously replicate to S3 only the cycles it owns to S3.

Overlapping replication cycles for asynchronous replication

The system, devices, and methods disclosed herein relate to a dynamic, robust method for choosing a 'winner' in an active-active data storage network. In the systems and methods disclosed herein, two or more intelligent nodes within an active-active data storage network periodically exchange operational parameters in an ongoing negotiation regarding who should be the winner in the event of a communication failure within the network. The winner is chosen dynamically based on the operational parameters. A witness is kept apprised of the winner. In the event of a communication failure between the two nodes, the winner is chosen by the witness based on the most recently negotiated lock file reported by one or both of the nodes.

Environmental aware witness for active-active storage cluster nodes

Techniques are described for processing multi-page write operations to maintain write level consistency. A multi-page write spanning multiple cache pages is directed to a target device and received on a first data storage system where writes to the target device are synchronously replicated to a second data storage system. On the first data storage system, each of the multiple cache pages may be synchronously replicated to the second data storage system. A lock on each of the cache pages is not released until an acknowledgement is received regarding successful replication of the cache page. On the second data storage system, requests to replicate the multiple cache pages containing write data of the multi-page write are received and processed using locks of corresponding cache pages on the second data storage system. Such techniques also handle concurrent reads and/or writes. Deadlock detection and resolution processing may be performed for concurrent writes.

Maintaining write consistency on distributed multiple page writes

Maintaining write consistency between at least two mirrored storage devices includes receiving a write request for a particular block, obtaining a reservation for the particular block, waiting for the particular block to become available in response to not being able to successfully obtain the reservation, writing the particular block in response to successfully obtaining the reservation, and writing the particular block at a remote one of the storage devices following writing the particular block at the particular one of the storage devices. If a retryable indicator is received, the system waits a predetermined amount of time and releases the reservation. The system responds with a success indicator when writing the particular block at a remote one of the storage devices succeeds and responds with a failure indicator when writing the particular block at a remote one of the storage devices fails and the retryable indicator is not received.

Multi-site block level write consistency

Described are data replication techniques. Y cycles of writes directed to a first storage device of a first data storage system are collected, Y&#x3e;2. Each of the Y cycles denotes writes directed to the first storage device at an occurrence of a fixed time interval. Writes of cycle N&#x2212;1 directed to the first storage device are transmitted from the first data storage system to a second data storage system. Writes of cycle N&#x2212;2 are applied to a second storage device. An acknowledgement regarding cycle N&#x2212;1 is sent from the second data storage system to the first data storage system responsive to determining that the writes of cycle N&#x2212;1 directed to the first storage device have been received by the second data storage system and that the writes of cycle N&#x2212;2 directed to the first storage device have been applied to the second storage device.

Data transfer techniques with data replication

Managing reservations for at least two different sites competing for a resource includes maintaining a table of groups of sites, where each group competes for the same resource, one of the different sites requesting a reservation for a particular resource, determining if the reservation is available by consulting the table, denying the reservation to the one of the at least two different sites in response to access having been previously reserved for an other one of the different sites, and granting the reservation to the one of the at least two different sites and reserving access for the one of the at least two different sites in response to the resource being available. The managed resources may correspond to data storage and the two different sites may be mirrored storage devices. In response to a failure of communication between the two different sites, pending writes may be failed.

Stateless witness for multiple sites

Providing multiple witnesses that manage resources for at least two different sites includes one of the sites choosing a particular one of the witnesses, the one of the at least two different sites confirming that the particular one of the witnesses is available to manage resources, the one of the at least two different sites communicating with other ones of the at least two different sites to determine if the particular one of the witnesses is acceptable to the other ones of the at least two different sites, and choosing the particular one of the witnesses in response to the particular one of the witnesses being available to manage resources and the particular one of the witnesses being acceptable to all of the other ones of the at least two different sites. The managed resources may correspond to data storage and the sites may be mirrored storage devices.

Multiple available witnesses

Growing community of inventors

Framingham, MA, United States of America

Benjamin W Yoder