Systems and methods, including computer program products, providing high-availability in server systems. In one implementation, a server system is cluster of two or more autonomous server nodes, each running one or more virtual servers. When a node fails, its virtual servers are migrated to one or more other nodes. Connectivity between nodes and clients is based on virtual IP addresses, where each virtual server has one or more virtual IP addresses. Virtual servers can be assigned failover priorities, and, in failover, higher priority virtual servers can be migrated before lower priority ones. Load balancing can be provided by distributing virtual servers from a failed node to multiple different nodes. When a port within a node fails, the node can reassign virtual IP addresses from the failed port to other ports on the node until no good ports remain and only then migrate virtual servers to another node or nodes.

High-availability cluster virtual server system

A high availability, high reliability storage system (215) that leverages rapid advances in commodity computing devices and the robust nature of internetwork technology such as the Internet (213). A system of parity distribution (505) in accordance with the present invention allows for greater fault tolerance and levels of storage efficiency than possible with conventional RAID (levels 0-5) paradigms. Data can be recovered or made available even in the case of loss of N, N+1, or more devices or storage elements (215) over which stripes of the data set have been distributed or partitioned. The present invention provides a parity distribution that can be used to distribute data stored in a single storage device or across multiple connected or otherwise networked devices.

System and method for data protection with multidimensional parity

In a computer network system, a user-defined file modification request is communicated to a primary server, which communicates the request to a secondary server. The file modification request is saved in a non-volatile storage media associated with the primary server, and the file modification request is executed and saved in a non-volatile storage media associated with the secondary server.

Real time backup system

Resource requests made by clients of origin servers in a network are intercepted by reflector mechanisms and selectively reflected to other servers called repeaters. The reflectors select a best repeater from a set of possible repeaters and redirect the client to the selected best repeater. The client then makes the request of the selected best repeater. The resource is possibly rewritten to replace at least some of the resource identifiers contained therein with modified resource identifiers designating the repeater instead of the origin server.

Optimized network resource location

An on-line services network includes application servers and Gateway microcomputers that are interconnected by a LAN. The Gateway microcomputers receive service requests which are transmitted over a WAN from client microcomputers operated by end users. Upon receiving a request to open a service, the Gateway microcomputers access a periodically-updated service map to locate the replicated application servers that are currently running the corresponding service application, and then apply a load balancing method (using server load data contained within the service map) to select an application server that has a relatively low processing load. A communications protocol between the client and Gateway microcomputers enables users to access multiple services simultaneously. A hot redirection technique allows a user service session to be transferred from one application server to another (replicated) application server without termination of the service session. Various mechanisms are provided for efficiently reallocating application servers to different on-line services, and for allowing additional servers to be efficiently added to the network.

Method of redirecting a client service session to a second application server without interrupting the session by forwarding service-specific information to the second server

An Integrity Server computer for economically protecting the data of a computer network's servers, and providing hot standby access to up-to-date copies of the data of a failed server. As the servers' files are created or modified, they are copied to the Integrity Server. When one of the servers fails, the Integrity Server fills in for the failed server, transparently providing the file service of the failed server to network clients. The invention provides novel methods for managing the data stored on the Integrity Server, so that the standby files are stored on low-cost media such as tape, but are quickly copied to disk when a protected server fails. The invention also provides methods for re-establishing connections between clients and servers, and communicating packets between network nodes, to allow the Integrity Server to stand-in for a failed server without requiring reconfiguration of the network clients.

Stand-in Computer file server providing fast recovery from computer file server failures

An Integrity Server computer for economically providing a stand-in computer, replacing a failed server of a network. The invention provides methods for re-establishing connections between clients and servers, and communicating packets between network nodes, to allow the Integrity Server to stand-in for a failed server without requiring reconfiguration of the network clients when a server fails. In one method, the Integrity Server publishes the name of the failed server, in addition to its normal name, when the failed server becomes inaccessible. In a second method, a first channel accepts network packets addressed to the failed server, and forwards them to a second channel for service.

Stand-in computer server

An Integrity Server computer for economically protecting the data of a computer network's servers, and providing hot standby access to up-to-date copies of the data of a failed server. As the servers' files are created or modified, they are copied to the Integrity Server. The invention provides novel methods for managing the data stored on the Integrity Server, so that up-to-date snapshots of files of the protected file servers are stored on low-cost media such as tape, but without requiring that a system manager load large numbers of tapes.

Christopher W. Midgely

Papers

Stand-in Computer file server providing fast recovery from computer file server failures

Stand-in computer server

Continuously-snapshotted protection of computer files