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 HP OpenVMS SystemsClusters |
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Providing highly available, unlimited high-end computing for your business needs
Expanding the limits of the world's leading clusters Compaq Computer Corporation - the pioneer of cluster technology since 1984 and industry leader ever since - continues to develop systems that are more reliable, faster, and more affordable. And at the same time ensuring that existing systems are compatible within new OpenVMS(TM) Clusters.With more than 50,000 clusters installed and supported worldwide, Compaq's support for OpenVMS clustering capabilities continues to improve, with additional features being added with every release. Apply this high performance technology to your business-critical computing needs--the ones that keep your orders flowing, money moving, and customers happy. Then relax knowing that your OpenVMS cluster system has the high availability--or even disaster tolerance capabilities--you need to stay in business. What is an OpenVMS Cluster? An OpenVMS Cluster is a highly integrated organization of Alpha and/or VAX(TM) computer systems, application and operating system software, and storage devices. The systems can be connected to each other and storage components in a variety of ways, depending on the needs of your business. OpenVMS Cluster systems give you the ultimate in a highly available, scalable, and flexible computing environment. The cluster also allows you to connect systems of all sizes and capacities and achieve an easy-to-manage, single virtual system.OpenVMS Clusters offer a wide range of potential configurations. Any business--from the smallest office to the largest enterprise-- can profit from the benefits of clusters. The unlimited high-end server for OpenVMS and Windows NT environments Compaq recently joined forces with Microsoft Corporation to deliver the mission critical, bet-your-business capabilities of OpenVMS to Windows NT(TM) applications. Using OpenVMS Clusters as the server system for Windows NT clients provides the bullet-proof, high availability computing advantages for which OpenVMS clusters are legendary.24x365 computing If your business demands that your computer system is ALWAYS available, OpenVMS is your only choice. Compaq supports a wide range of approaches to high availability to meet your specific computing requirements--24 hours a day, 365 days a year. All of our solutions have been designed and tested to work in today's multivendor client/server environment.When a single system shuts down in a traditional single-system computing environment or in many other "cluster systems" no other system on the network can access the information on its disks, resulting in costly downtime. With OpenVMS Cluster configurations, you can connect storage subsystems to I/O interconnects that can be accessed by multiple systems. This means that if a node shuts down, all remaining nodes in the OpenVMS Cluster still have access to its applications and data. Scalable and flexible With OpenVMS Clusters, you can expand your server configurations from the low-end to the high-end without having to trade in or retire your hardware investments. Start with a single VAX or Alpha system and, when you need to increase computing power, simply add another system to the cluster--without replacing existing systems or applications. They all work together running the powerful, business-critical OpenVMS operating system.Since Compaq's clustering capabilities range from clusters of two systems to 96 systems, they scale to meet your needs. And with numerous connection capabilities, you can be assured that the correct technology will be applied to your business needs--whether your business requires extraordinarily fast I/O, massive storage capabilities, or the need to add new systems to current OpenVMS clusters. Disaster tolerance OpenVMS Clusters can be configured into disaster tolerant multisite clusters located up to 500 miles (800 kilometers) apart. With distances of this magnitude, natural or man-made disasters that could potentially put you out of business are no longer threats. Regional disasters such as earthquakes, power outages, floods, and fires are virtually eliminated as interruptions to your business.Within your OpenVMS cluster, CPUs retain their independence--yet greatly benefit from common resources such as shared processing resources, data storage, tape drives, and batch and print queues. No single point of failure can bring an application down. As Datamation says, "According to a survey of 400 large companies conducted by Oracle, downtime costs a company $1400 per minute, on average. Based on these figures, 43 hours of downtime per year would cost $3.6 million. One hour of downtime per year amounts to $84,000 per year." (Datamation August 15, 1995)
Technical Features OpenVMS Clusters provide the full spectrum of cluster features that you would expect in a leadership product. For example:
OpenVMS Clusters provide the best clustering features in the industry!
OpenVMS Clustering Interconnect Choices Select one that meets your needs, or mix interconnects when your needs change! Systems and storage in an OpenVMS Cluster exchange information by means of physical communication links known as interconnects. OpenVMS Clusters offer a range of interconnect choices including:
SCSI--the Small Computer Storage Interconnect Standard The ideal starting point for configuring a low-end, affordable cluster solution With SCSI-based clusters, you can use commodity-priced storage devices directly in OpenVMS Clusters of Alpha systems. SCSI is an industry-based standard bus based on the work of the American National Standards Institute (ANSI). It defines the ways in which peripheral devices can access a standard, general-purpose bus and has become the key design standard for increasingly small, fast, reliable, and low-cost storage devices.SCSI clusters can range from desktop and deskside to the largest configurations. They can be configured with no single point of failure. Compaq contributed extensively to the development of this standard and takes fullest advantage of the current protocol (SCSI-2) in SCSI-based OpenVMS Clusters to deliver high performance and availability. Choices indistance, cost, and performance The SCSI interconnect in an OpenVMS Cluster provides a balance of distance, price, performance, and storage capacity. Transfer rates now range from 10 to 20 megabytes/second as the SCSI bus has been improved over the years. The maximum length of the SCSI interconnect is 25 meters using differential devices.Example: SCSI-based OpenVMS Cluster using two SCSI buses with directly attached disks
The configuration above comprises a small, two-node cluster with directly attached disks. This configuration does not require a separate storage controller, thereby reducing the cost. Like all other OpenVMS Clusters, it can be configured with a single system disk from which both nodes can boot. For higher availability the system disk could be shadowed (using the OpenVMS Volume Shadowing host-based RAID-1 product) to a disk on the second SCSI bus. A tie-breaking Quorum Disk can also be located on one of the SCSI buses. The configuration could be expanded by the addition of a third Alpha system, and another four shared SCSI buses (up to six in total). Example: SCSI-based OpenVMS Cluster using FWD HSZ Controllers
The SCSI Hub in the example above comprises a BA356 StorageWorks rack filled with up to 5 DWZZB level converters. A single FWD SCSI cable is run from each DWZZB to a system or storage controller. This style of "star" configuration provides up to 20 meters of radial connectivity and easier maintenance because each SCSI cable is individually terminated. OpenVMS Memory Channel (MC) Memory Channel (available with OpenVMS V7.1) is a new high performance interconnect for PCI-based Alpha systems in OpenVMS clusters. Memory Channel supports all cluster features - as do all existing cluster interconnects - without any changes required to your existing software.Memory Channel delivers high performance node-to-node communication, while a separate interconnect, such as CI, SCSI, or DSSI is used to provide access to storage. Compaq developed Memory Channel to provide high-performance OpenVMS lock manager capabilities for today's VLDB (Very Large Database) implementations, such as Oracle. Example: OpenVMS Cluster based on Memory Channel and SCSI 
Computer Interconnect (CI)
Gain fast, efficient access to large amounts of data When connecting datacenter VAX systems, Alpha systems, and independent storage devices to form a cluster, CI allows for extremely high-speed, dual-path communications for large systems and I/O-intensive applications. It permits efficient access to huge amounts of data while providing redundant data paths (140 megabits per second). CI clusters offer the highest levels of availability and throughput since systems and storage devices are dual pathed. A CI component, the Star Coupler, allows center connection of up to 32 nodes (systems or storage devices) in a "star-shaped" OpenVMS Cluster.Example: CI-based OpenVMS Cluster comprised of Alpha and VAX systems 
Local Area Network (LAN) interconnects: Ethernet and FDDI Ethernet: an affordable, flexible, network medium The Ethernet, an industry-standard network interconnect of single path connections, provides the backbone for low-cost OpenVMS Clusters or local area networks. Ethernet-based OpenVMS Clusters can connect up to 96 systems. In addition to normal 10Mb/sec Ethernet, high speed 100Mb/sec Fast Ethernet configurations are also supported by OpenVMS Cluster software.FDDI: links multiple sites into a single operating environment An ANSI and IEEE standard for high-speed, multivendor networking interconnections, FDDI extends cluster availability to multiple physical sites (up to 25 miles/40 kilometers apart) to form a single operating environment consisting of up to 96 systems. FDDI uses high-speed fiberoptic cable as a transmission medium. Computing resources that are currently physically located outside your data center can now be tied into it using FDDI.FDDI can be used to create disaster-tolerant OpenVMS Clusters. Linking sites using DS3, asynchronous transfer mode (ATM), and microwave technology is possible using FDDI in conjunction with Compaq's Gigaswitch bridging product. Example: Disaster Tolerant OpenVMS Cluster comprising two sites with SCSI and DSSI based configurations 
Digital Storage Systems Interconnect (DSSI) Providing a low-cost connection for clusters containing Alpha and VAX systems Used in office and datacenter environments, DSSI links VAX systems, Alpha systems, and intelligent storage devices into multihost configurations through a low-cost DSSI bus. DSSI permits systems to communicate directly with each other, and can connect up to four nodes in an OpenVMS Cluster. Most DSSI clusters utilize multiple buses.Example: DSSI-based OpenVMS Cluster 
Mixed Interconnect Combine interconnects the way you want . . . the way you needOne of the advantages of an OpenVMS Cluster is that it allows you to mix interconnects to meet your needs. The best choice depends upon your performance requirements. Four of the most critical factors to consider include:
The configuration above shows how multiple interconnects can be used within a single cluster. The two VAX systems and four Alpha systems are all connected to the CI bus, and can directly access the HSJ-based storage subsystems. Additionally, the Alpha systems are connected to a Memory Channel which offloads their node-to-node traffic from the CI. Lastly, three of the Alpha systems share a FWD SCSI-based storage subsystem. The disks in this subsystem can be accessed by the VAXs and the small Alpha through MSCP disk server software running on the large Alphas.
Compaq's OpenVMS Cluster Interconnects At-a-Glance
When it comes to benefits, nothing comes close to OpenVMS ClustersCompaq's OpenVMS Clusters give you the confidence that your business will stay up and running at all times. Your business will be secure with high-performance systems that deliver constant, disaster-proof access to your applications and data. And as your requirements change and expand, OpenVMS Cluster technology will accommodate your growth and shifting needs without disrupting day-to-day business functions. Ordering InformationOpenVMS Cluster Software is orderable as follows:Every server (non-client) Alpha system in a OpenVMS Cluster configuration requires:
Refer to your local price book for pricing information.
Updated by: OpenVMS Cluster Product Marketing - 1 May 1998
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