Abstract: A blade-based distributed computing system, for applications such as a storage network system, is made highly-available. The blade server integrates several computing blades and a blade for a switch that connects to the computing blades. Redundant components permit failover of operations from one component to its redundant component. Configuration of one or more blade servers, such as assignment of high level network addresses to each blade, can be performed by a centralized process, called a configuration manager, on one blade in the system. High level network addresses can be assigned using a set of sequential network addresses for each blade server. A range of high level network addresses is assigned to each blade server. Each blade server in turn assigns high level network addresses to its blades. The high level network address for each blade can be mapped to its chassis identifier and slot identifier. Configuration information also may include software version information and software upgrades.

Abstract: Segments or blocks of a file can be distributed among an number n of storage units by using a function of sequentially assigned segment identifiers for each segment, where the function is reduced modulo n, so long as the function is not congruent to segment identifier, modulo n, for any given segment identifier. An example of such a function, where n is the number of storage units and k is a segment identifier, is f(k)=ak+b, where a is relatively prime to n. Such a function can be computed quickly for any given segment. As the list of storage units changes, data may be redistributed using a new mapping of segments to storage units. Any new mapping can be restricted so that segments only move to a new storage unit or from an old storage unit, and not from one existing storage unit to another. In this way, the amount of data to be moved is limited. A chain of the lists of available storage units, as that list changes over time, is maintained to permit the history of file mappings to be recreated.

Abstract: A technique for sharing a resource among a cluster of devices in a computer network. The technique involves generating a vote count that includes votes from voting devices attempting to form a cluster until the vote count reaches a quorum. The technique further involves, when the quorum is reached, selecting a most advanced generation indicator from among the voting devices, advancing the selected generation indicator and storing the advanced selected generation indicator in memory as a cluster generation indicator. Upon the advanced selected generation indicator being stored in memory, the cluster is formed and includes the voting devices. The technique further involves sharing a resource among the voting devices after the cluster is formed.