Emc IP Holding Company LLC

Svetlana Sokolova

Deepak Vokaliga

Benjamin W Yoder

Arieh Don

Mark J Halstead

Subin George

Architectures and techniques are described that can enhance the functionality of a witness for an active-active storage array. In the event of a dual storage area network (SAN) failure, or another suitable event, host-array connectivity can take precedence for the witness in determining a winner or loser. Techniques are presented to identify connectivity issues and to utilize connectivity data in connection with determining a winner or a loser.

Connectivity-aware witness for active-active storage

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

Described are techniques for maintaining and using registration and reservation information in an active-active configuration that provides automated data replication of a logical device. Various commands may be issued from one or more hosts to read and modify registration and reservation information in the active-active configuration. Processing is performed to service the various commands and provide a host or client with a consolidated logical view of a data storage system including the logical device where the host is allowed to issue I/Os over multiple paths to the logical device. Depending on the command, such processing may include replicating or mirroring reservation state information between two data storage systems each including a different device configured as the logical device.

Managing registration and reservation information in an active-active configuration

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.

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Framingham, MA, United States of America

Svetlana Sokolova