Reliability and availability of distributed servers

摘要

A system of network proxies distributes data to multiple servers. Each network proxy is associated with a server. A network proxy intercepts a client request for data. If the network proxy determines that the request can be served using a copy of data stored on the local server, rather than the data stored on a remote server, it diverts the request to the local server. If the network proxy determines that the request cannot be served using a data from the local server, the network proxy diverts the request to a remote server storing the primary copy of the data. A server map specifies the locations of the primary copies of data. When a primary copy of data is updated on one of the servers, the associated network proxy propagates the updated data to the other servers. The servers can provide data from files, e-mail services, databases, or multimedia services.

主权项

1. A distributed system comprising:
a first network proxy adapted to interface with a first client and a first server, wherein the first server includes a first copy of data; and a second network proxy adapted to interface with the first network proxy and a second server, wherein the second server includes a second copy of the data; wherein the first network proxy includes logic adapted to receive a write request to modify the data from the first client, logic adapted to locate a primary copy of the data, logic adapted to respond to the write request by modifying the first copy of the data on the first server if the first copy is determined to be the primary copy of the data, and logic adapted to respond to the write request by forwarding the write request to the second network proxy if the second copy of the data is the primary copy, wherein the logic adapted to locate a primary copy of the data includes logic to access a server map specifying a relationship between a shared directory of the first server and a shared directory of the second server, and wherein the server map designates a shared directory including the primary copy of the data as a local directory and a shared directory including a non-primary copy of the data as a broadcast directory.