Emc IP Holding Company LLC

Ronald C Unrau

Assaf Natanzon

Saar Cohen

Victor Salamon

Steven Richard Bromling

Brian Lake

Paul A Shelley

Qinghua Ye

A cache coherency protection system provides for data redundancy by sharing a cache coherence memory pool for protection purposes. The system works consistently across all communication protocols, yields improved data availability with potentially less memory waster and makes data availability faster in node/director failure scenarios. According to various embodiments, the cache coherency protection system may include a writer/requester director that receives a write request from host, a protection target director that is a partner of the writer/request director and a directory.

Cache protection through cache

Handling I/O operations between a plurality of virtual machines and a plurality of data storage volumes containing data for the virtual machines includes the virtual machines accessing a virtual data storage cluster engine that transfers I/O data between the virtual machines and the data storage volumes and caches at least some of the I/O data, where the virtual data storage cluster appears as a data storage volume to the virtual machines and includes drivers of at least some of the virtual machines routing at least some I/O operations directly to the volumes, where data for I/O operations that is directly routed does not pass through the virtual data storage cluster engine. Drivers for at least one of the virtual machines on a local site may communicate with drivers on a remote site in response to performing an I/O operation with at least one volume on the remote site.

Out of band I/O transfers

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CA

Ronald C Unrau