| US 7,475,207 B2 | ||
| Maintaining write order fidelity on a multi-writer system | ||
| Steve Bromling, Edmonton (Canada); Dale Hagglund, Edmonton (Canada); Geoff Hayward, Edmonton (Canada); Roel Van der Goot, Edmonton (Canada); and Wayne Karpoff, Sherwood Park (Canada) | ||
| Assigned to EMC Corporation, Hopkinton, Mass. (US) | ||
| Filed on Jul. 14, 2006, as Appl. No. 11/486,754. | ||
| Claims priority of provisional application 60/699935, filed on Jul. 14, 2005. | ||
| Prior Publication US 2007/0022264 A1, Jan. 25, 2007 | ||
| Int. Cl. G06F 12/00 (2006.01) | ||
| U.S. Cl. 711—162 [711/148; 709/214] | 35 Claims |
| 1. A method of providing write order fidelity in a distributed set of data access nodes in a network, comprising the steps
of:
storing a write request to a first cache for an open delta, the first cache corresponding to a first node receiving the write
request;
transmitting a message, in response to a triggering event, to each node in the set of data access nodes to close the open
delta;
for each node having a write request for the open delta, completing any pending write requests for the open delta and closing
the open delta;
exchanging write request information among nodes so that each node is associated with a complete copy of the write request
information for the closed delta;
writing each complete copy to persistent storage;
storing each complete copy of the closed delta to back-end storage for each node; and
grouping front-end volumes into write-order fidelity (WOF) groups, each WOF group including at least one site across the network.
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