OpenVMS Cluster Software is an OpenVMS System Integrated Product (SIP). It provides a highly integrated OpenVMS computing environment distributed over multiple Integrity server systems, or in mix of AlphaServer and Integrity server systems.
Systems in an OpenVMS Cluster system can share processing, mass storage (including system disks), and other resources under a single OpenVMS security and management domain. Within this highly integrated environment, systems retain their independence because they use local, memory-resident copies of the OpenVMS operating system. Thus, OpenVMS Cluster systems can boot and shut down independently while benefiting from common resources.
Applications running on one or more systems in an OpenVMS Cluster system can access shared resources in a coordinated manner. OpenVMS Cluster software components synchronize access to shared resources, allowing multiple processes on any system in the OpenVMS Cluster to perform coordinated, shared data updates.
Because resources are shared, OpenVMS Cluster systems offer higher availability than standalone systems. Properly configured OpenVMS Cluster systems can withstand the shutdown or failure of various components. For example, if one system in an OpenVMS Cluster is shut down, users can log in to another system to create a new process and continue working. Because mass storage can be shared clusterwide, the new process is able to access the original data. Applications can be designed to survive these events automatically.
All OpenVMS Cluster systems have the following software features in common:
- The OpenVMS operating system and OpenVMS Cluster software allow all systems to share read and write access to disk files in a fully coordinated environment. Application programs can specify the level of clusterwide file sharing that is required; access is then coordinated by the OpenVMS extended QIO processor (XQP) and Record Management Services (RMS). Coherency of multiple-system configurations is implemented by OpenVMS Cluster software using a flexible and sophisticated per-system voting mechanism.
- Shared batch and print queues are accessible from any system in the OpenVMS Cluster system. The OpenVMS queue manager controls clusterwide batch and print queues, which can be accessed by any system. Batch jobs submitted to clusterwide queues are routed to any available system so the batch load is shared.
- The OpenVMS Lock Manager system services operate in a clusterwide manner. These services allow reliable, coordinated access to any resource, and provide signaling mechanisms at the system and process level across the whole OpenVMS Cluster system.
- All disks and tapes in an OpenVMS Cluster system can be made accessible to all systems.
- Process information and control services, including the ability to create and delete processes, are available on a clusterwide basis to application programs and system utilities.
- Configuration command procedures assist in adding and removing systems and in modifying their configuration characteristics.
- The dynamic Show Cluster utility displays the status of OpenVMS Cluster hardware components and communication links.
- A fully automated clusterwide data and application caching feature enhances system performance and reduces I/O activity.
- The ability to define logical names that are visible across multiple nodes in an OpenVMS Cluster.
- An application programming interface (API) allows applications within multiple OpenVMS Cluster nodes to communicate with each other.
- Standard OpenVMS system management and security features work in a clusterwide manner so that the entire OpenVMS Cluster system operates as a single security and management domain.
- The OpenVMS Cluster software dynamically balances the interconnect I/O load in OpenVMS Cluster configurations that include multiple interconnects.
- Multiple OpenVMS Cluster systems can be configured on a single or extended local area network (LAN). LANs and the LAN adapters used for OpenVMS Cluster communications can be used concurrently by other network protocols.
- OpenVMS Clusters Software features the Cluster over IP functionality, which provides the ability to form clusters beyond a single LAN or VLAN segment using industry standard Internet Protocol. This feature provides improved disaster tolerant capability.
- The optionally installable Availability Manager (as well as the DECamds availability management tool) allows system managers to monitor and manage resource availability in real time on all the members of an OpenVMS Cluster.
- Satellite boot support on Integrity server systems is available.
- System services enable applications to automatically detect changes in OpenVMS Cluster membership.