Netapp, Inc.

Orly Devor

Yoram Novick

Erez Webman

Dvir Koren

Lior Oded Bahat

Ofer Elrom

A software upgrade tool and procedure provide uninterrupted operation of a replication system during an upgrade of software components of the system. The replication system includes one or more user systems coupled to one or more target storage systems over a communications network, such as a computer network. Illustratively, each user system is embodied as a replication client, while each target storage system is embodied as a replication server. In addition, the replication system includes a management system embodied as a management server that manages configuration of the system, including during upgrade of the software components of the replication system. To that end, the software upgrade tool cooperates with the management server to query the configuration of 'old' versions of the software components and to manage upgrades of those components to 'new' versions of software. According to the invention, the upgrade tool and procedure enable both the old and new versions of the software components to run concurrently on the replication client and replication server, as well as the management server.

System and method for providing uninterrupted operation of a replication system during a software upgrade

A delta query technique transmits only latest changes to data of objects from a server to one or more clients in response to a client query (request) to access the object data. A global counter is maintained for all of the objects served by the server. Every time the data of an object changes, a value of the global counter increments (updates) and the updated global counter value is then assumed ('inherited') by that object. In addition, the global counter is updated when a client issues a request to access one or more objects. If the data of the objects has changed since the last time the client accessed the objects, the server responds with the latest object data and the updated global counter value. Notably, each client maintains a local counter having a value that, upon receipt of the latest object data, is modified to reflect the updated global counter value.

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Zichron Yaakovv, Israel

Orly Devor