HP OpenVMS Systems Documentation
Guidelines for OpenVMS Cluster Configurations
2.2.5 Other Configuration Aids
In addition to these utilities and partner products, several commands are available that allow the system manager to set parameters on HSC, HSJ, HSD, HSZ, HSG, and RF subsystems to help configure the system. See the appropriate hardware documentation for more information.
|System Type||Useful for||Examples|
Users who require their own systems with high processor performance.
Examples include users running mechanical computer-aided design,
scientific analysis, and data-reduction and display applications.
Workstations offer the following features:
Midrange office computing. Departmental systems offer the following
|Data center systems||
Large-capacity configurations and highly available technical and
commercial applications. Data center systems have a high degree of
expandability and flexibility and offer the following features:
AlphaServer GS60, GS80
AlphaServer GS160, GS320
When you choose a system based on scalability, consider the following:
An OpenVMS Cluster system is a highly integrated environment in which multiple systems share access to resources. This resource sharing increases the availability of services and data. OpenVMS Cluster systems also offer failover mechanisms that are transparent and automatic, and require little intervention by the system manager or the user.
The following factors affect the performance of systems:
With these requirements in mind, compare processor performance, I/O
throughput, memory capacity, and disk capacity in the Alpha and VAX
specifications that follow.
3.7 System Specifications
The Compaq World Wide Web (WWW) site provides ordering and configuring information for Alpha and Intel workstations and servers. It also contains detailed information about storage devices, printers, and network application support.
To access the Compaq WWW site, use the following URL:
An interconnect is a physical path that connects computers to other computers, and to storage subsystems. OpenVMS Cluster systems support a variety of interconnects (also referred to as buses) so that members can communicate with each other and with storage, using the most appropriate and effective method available.
The software that enables OpenVMS Cluster systems to communicate over an interconnect is the System Communications Services (SCS). An interconnect that supports node-to-node SCS communications is called a cluster interconnect. An interconnect that provides node-to-storage connectivity within a cluster is called a shared-storage interconnect. Some interconnects, such as CI and DSSI, can serve as both cluster and storage interconnects.
The interconnects described in this chapter share some general characteristics. Table 4-1 describes these characteristics.
The quantity of data transferred across the interconnect.
Some interconnects require more processor overhead than others. For example, Ethernet and FDDI interconnects require more processor overhead than do CI or DSSI.
Larger packet sizes allow higher data-transfer rates (throughput) than do smaller packet sizes.
|Cable length||Interconnects range in length from 3 m to 40 km.|
|Maximum number of nodes||The number of nodes that can connect to an interconnect varies among interconnect types. Be sure to consider this when configuring your OpenVMS Cluster system.|
|Supported systems and storage||Each OpenVMS Cluster node and storage subsystem requires an adapter to connect the internal system bus to the interconnect. First consider the storage and processor I/O performance, then the adapter performance, when choosing an interconnect type.|
Table 4-2 shows key statistics for a variety of interconnects.
|Interconnect||Maximum Throughput (Mb/s)||Hardware-Assisted Data Link1||Storage Connection||Topology||Maximum Nodes per Cluster||Maximum
|ATM||155/622||No||MSCP served||Radial to a switch||96 2||2 km 3/300 m 3|
|10/100/1000||No||MSCP served||Linear or radial to a hub or switch||96 2||100 m 4/100 m 4/550 m 3|
|FDDI||100||No||MSCP served||Dual ring to a tree, radial to a hub or switch||96 2||40 km 5|
|CI||140||Yes||Direct and MSCP served||Radial to a hub||32 6||45 m|
|DSSI||32||Yes||Direct and MSCP served||Bus||8 7||6 m 8|
|Fibre Channel||1000||No||Direct 9||Radial to a switch||96 2||
/100 km 11
|SCSI||160||No||Direct 9||Bus or radial to a hub||8-16 12||25 m|
|Node-to-node (SCS traffic only)|
|MEMORY CHANNEL||800||No||MSCP served||Radial||4||3 m|
A mixed interconnect is a combination of two or more different types of
interconnects in an OpenVMS Cluster system. You can use mixed
interconnects to combine the advantages of each type and to expand your
OpenVMS Cluster system. For example, an Ethernet cluster that requires
more storage can expand with the addition of Fibre Channel, SCSI, or CI
4.5 Interconnects Supported by Alpha and VAX Systems
Table 4-3 shows the OpenVMS Cluster interconnects supported by Alpha and VAX systems.
You can also refer to the most recent OpenVMS Cluster SPD to see the latest information on supported interconnects.
|AlphaServer GS160, GS320||X||X||X||X||X||X||X|
|AlphaServer GS60, GS80, GS140||X||X 1||X||X||X||X||X|
|AlphaServer DS20E, DS10L, DS10||X||X||X||X||X||X||X|
|AlphaStation ES40||X||X||X||X||X||X 2||X|
|AlphaServer 8400, 8200||X||X||X||X 1||X||X||X||X|
|AlphaServer 4100, 2100, 2000||X||X||X 1||X 1||X||X||X||X 3|
|AlphaServer 1000||X||X||X||X 1||X||X|
|AlphaServer 400||X||X||X 1||X|
|DEC 7000/10000||X||X||X 1||X|
|DEC 4000||X||X||X 1|
|DEC 3000||X 1||X 1||X|
|DEC 2000||X||X 1|
|VAX 4000, MicroVAX 3100||X||X||X 1|
|VAXstation 4000||X||X 1|
In most cases, the I/O requirements will be less than the capabilities of any one OpenVMS Cluster interconnect. Ensure that you have a reasonable surplus I/O capacity, then choose your interconnects based on other needed features.
Reference:: For detailed information about the interconnects and adapters supported on each AlphaServer system, refer to the Compaq web site:
Under Products, select Servers, then AlphaServers, then the server family (for example, DS, ES, or GS), then the server model. You can then select from all supported options.
You can also select the Alpha Systems Technology Technical Information web page, from which you can access documentation, supported options, firmware updates, and the software patch service for each Alpha system model.