CLUSTER SPD.PDF

This document describes the OpenVMS Cluster Software, Version 6.2, a System Integrated Product (SIP) designed to create a highly integrated distributed computing environment for Digital Alpha and VAX CPUs.

Key Features and Benefits:

• Shared Resources & High Availability: CPUs within a VMScluster can share processing, mass storage (including system disks), and other resources under a single OpenVMS security and management domain. This provides higher availability and fault tolerance than standalone systems, allowing users to continue working on another CPU if one fails.
• Coordinated Access: The software synchronizes access to shared resources, enabling multiple processes across different CPUs to perform coordinated data updates.
• Comprehensive Resource Sharing: Includes shared read/write access to disk files (coordinated by XQP/RMS), clusterwide batch and print queues (for load sharing), and a clusterwide Lock Manager for reliable resource access. All physical disks and tapes can be made accessible to all CPUs.
• Performance Enhancement: Features automated clusterwide data and application caching to boost performance and reduce I/O activity.
• Flexible Configuration: Supports various interconnects including CI, DSSI, SCSI, FDDI, and Ethernet, with automatic failover to alternate paths. Can span Wide Area Networks (WANs) via FDDI bridges.
• Management & Monitoring: Includes utilities for configuration, dynamic status display (Show Cluster), and the DECamds availability management tool for real-time monitoring of resources, processes, and I/O activity across the cluster.
• Satellite Booting: Allows cross-architecture satellite booting, where VAX nodes can boot Alpha satellites and vice-versa.
• VMScluster Client: Client CPUs offer full VMScluster functionality, but cannot provide votes towards quorum or serve disks/tapes (MSCP/TMSCP).

Configuration and Requirements:

• Maximum Scale: Supports up to 96 CPUs in a VMScluster.
• Interconnect Rules: Specific rules apply to the number of CPUs per interconnect type (e.g., max 16 per star coupler, max 4 per DSSI, max 2 per multi-host SCSI bus). Dual-pathed storage is supported for enhanced data availability and failover.
• Software Basis: Requires OpenVMS Operating System Version 6.2.
• Mixed-Version Support: Provides migration support for mixed-architecture/mixed-version clusters (e.g., OpenVMS 6.2 with older versions), but Digital recommends and warrants configurations where all Alpha and VAX systems run OpenVMS Version 6.2.
• Optional DECnet: Not strictly required for VMScluster operation, but needed for inter-node process communication via mailboxes and certain Monitor utility functions.
• Licensing: Licensed per CPU (server or client), with DECamds functionality included in all licenses.

In essence, OpenVMS Cluster Software 6.2 provides a robust, scalable, and highly available computing environment by integrating multiple OpenVMS Alpha and VAX systems to share resources and process workloads collaboratively.