HP OpenVMS Systems Documentation

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HP OpenVMS Cluster Systems

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1.3 Software Components

The OpenVMS operating system, which runs on each node in an OpenVMS Cluster, includes several software components that facilitate resource sharing and dynamic adjustments to changes in the underlying hardware configuration.

If one computer becomes unavailable, the OpenVMS Cluster system continues operating because OpenVMS is still running on the remaining computers.

1.3.1 OpenVMS Cluster Software Functions

The following table describes the software components and their main function.
Component Facilitates Function
Connection manager Member integrity Coordinates participation of computers in the cluster and maintains cluster integrity when computers join or leave the cluster.
Distributed lock manager Resource synchronization Synchronizes operations of the distributed file system, job controller, device allocation, and other cluster facilities. If an OpenVMS Cluster computer shuts down, all locks that it holds are released so that processing can continue on the remaining computers.
Distributed file system Resource sharing Allows all computers to share access to mass storage and file records, regardless of the type of storage device (DSA, RF, SCSI, and solid state subsystem) or its location.
Distributed job controller Queuing Makes generic and execution queues available across the cluster.
MSCP server Disk serving Implements the proprietary mass storage control protocol in order to make disks available to all nodes that do not have direct access to those disks.
TMSCP server Tape serving Implements the proprietary tape mass storage control protocol in order to make tape drives available to all nodes that do not have direct access to those tape drives.

1.4 Communications

The System Communications Architecture (SCA) defines the communications mechanisms that allow nodes in an OpenVMS Cluster system to co-operate. SCA governs the sharing of data between resources at the nodes and binds together System Applications (SYSAPs) that run on different Integrity server systems and Alpha computers.

SCA consists of the following hierarchy of components:

Communications Software Function
System applications (SYSAPs) Consists of clusterwide applications (for example, disk and tape class drivers, connection manager, and MSCP server) that use SCS software for interprocessor communication.
System Communications Services (SCS) Provides basic connection management and communication services, implemented as a logical path between system applications (SYSAPs) on nodes in an OpenVMS Cluster system.
Port drivers Control the communication paths between local and remote ports.
Physical interconnects Consists of ports or adapters for CI, DSSI, Ethernet, ATM, FDDI, and MEMORY CHANNEL interconnects. PEDRIVER is the port driver for LAN (Ethernet) interconnect and starting with OpenVMS Version 8.4 PEDRIVER is also enabled to use TCP/IP for cluster communication.

1.4.1 System Communications

Figure 1-1 shows the relationship between OpenVMS Cluster components.

Figure 1-1 OpenVMS Cluster System Communications

In Figure 1-1, processes in different nodes exchange information with each other.

  • Processes can call the $QIO system service and other system services directly from a program or indirectly using other mechanisms such as OpenVMS Record Management Services (RMS). The $QIO system service initiates all I/O requests.
  • A SYSAP on one OpenVMS Cluster node communicates with a SYSAP on another node using a logical path called connection. For example, a connection manager on one node communicates with the connection manager on another node, or a disk class driver on one node communicates with the MSCP server on another node. The following SYSAPs use SCS for cluster communication:
    • Disk and tape class drivers
    • MSCP server
    • TMSCP server
    • DECnet class driver
    • Connection manager
    • SCA$TRANSPORT, which provides node-to-node communications to the intracluster communication (ICC) programming interface, available through ICC system services, and to the distributed queue manager
  • SCS routines provide connection setup and services to format and transfer SYSAP messages to a port driver for delivery over a specific interconnect.
  • Communications go through the port drivers to port drivers on other OpenVMS Cluster computers and storage controllers. A port driver manages a logical path, called a virtual circuit, between each pair of ports in an OpenVMS Cluster system. A virtual circuit provides reliable message delivery for the connections multiplexed upon it.
    Starting with OpenVMS Version 8.4, cluster systems can use Transmission Control Protocol and Internet Protocol (TCP/IP) stack for cluster communication. PEDRIVER is enhanced with the capability to use TCP/IP in addition to LAN for cluster communication. For more information, see Chapter 3.

1.4.2 Application Communications

Applications running on OpenVMS Cluster systems use TCP/IP, DECnet, or ICC for application communication.

ICC allows processes to efficiently exchange messages with processes running on other cluster members using system communications services and the underlying cluster interconnect. The DECnet and TCP/IP communication services allow processes to locate or start remote servers and then exchange messages.


The generic references to DECnet in this document mean either DECnet for OpenVMS or DECnet-Plus (formerly known as DECnet/OSI) software.

1.4.3 Cluster Alias

DECnet provides a feature known as a cluster alias. A cluster alias is a collective name for the nodes in an OpenVMS Cluster system.

Application software can use the cluster alias as the name to connect to a node in the OpenVMS Cluster. DECnet chooses the node to which the application makes a connection. The use of a cluster alias frees the application from keeping track of individual nodes in the OpenVMS Cluster system and results in design simplification, configuration flexibility, and application availability. It also provides a mechanism for load balancing by distributing incoming connections across the nodes comprising the cluster.

1.4.4 failSAFE IP

TCP/IP provides a feature known as a failSAFE IP that allows IP addresses to failover when interfaces cease functioning on a system, where multiple interfaces have been configured with the same IP address.

You can configure a standby failover target IP address that failSAFE IP assigns to multiple interfaces on a node or across the OpenVMS Cluster system. When, for example, a Network Interface Controller fails or a cable breaks or disconnects, failSAFE IP activates the standby IP address so that an alternate interface can take over to maintain the network connection. If an address is not preconfigured with a standby, then failSAFE IP removes the address from the failed interface until it recovers. When the failed interface recovers, failSAFE IP detects this and can return its IP address.

1.5 System Management

The OpenVMS Cluster system manager must manage multiple users and resources for maximum productivity and efficiency while maintaining the necessary security.

1.5.1 Ease of Management

An OpenVMS Cluster system is easily managed because the multiple members, hardware, and software are designed to co-operate as a single system:

  • Smaller configurations usually include only one system disk (or two for an OpenVMS Cluster configuration with both OpenVMS Alpha and OpenVMS Integrity server operating systems), regardless of the number or location of computers in the configuration.
  • Software must be installed only once for each operating system (Alpha or Integrity servers), and is accessible by every user and node of the OpenVMS Cluster.
  • Users must be added once to access the resources of the entire OpenVMS Cluster.
  • Several system management utilities and commands facilitate cluster management.

Figure 1-2 illustrates centralized system management.

Figure 1-2 Single-Point OpenVMS Cluster System Management

1.5.2 HP Tools and Utilities

The OpenVMS operating system supports a number of utilities and tools to assist you with the management of the distributed resources in OpenVMS Cluster configurations. Proper management is essential to ensure the availability and performance of OpenVMS Cluster configurations.

OpenVMS and its partners offer a wide selection of tools to meet diverse system management needs. Table 1-2 describes the HP products available for cluster management and indicates whether each is supplied with the operating system or is an optional product, which is purchased separately. For information about OpenVMS Partners and the tools they provide, see the OpenVMS System Management website:


Table 1-2 HP System Management Tools
Tool Supplied or Optional Function
VMS Accounting Supplied Tracks how resources are being used.
Configuration and capacity planning
LMF (License Management Facility) Supplied Helps the system manager determine which software products are licensed and installed on a standalone system and on each computer in an OpenVMS Cluster system.
SYSGEN (System Generation) utility Supplied Allows you to tailor your system for a specific hardware and software configuration. Use SYSGEN to modify system parameters, load device drivers, and create additional page and swap files.
CLUSTER_CONFIG.COM Supplied Automates the configuration or reconfiguration of an OpenVMS Cluster system and assumes the use of DECnet.
CLUSTER_CONFIG_LAN.COM Supplied Automates configuration or reconfiguration of an OpenVMS Cluster system without the use of DECnet.
HP Management Agents for OpenVMS Supplied Consists of a web server for system management with management agents that allow you to look at devices on your OpenVMS systems.
HP Insight Manager XE Supplied with every HP NT server Centralizes system management in one system to reduce cost, improve operational efficiency and effectiveness, and minimize system down time. You can use HP Insight Manager XE on an NT server to monitor every system in an OpenVMS Cluster system. In a configuration of heterogeneous HP systems, you can use HP Insight Manager XE on an NT server to monitor all systems.
Event and fault tolerance
OPCOM message routing Supplied Provides event notification.
Operations management
Clusterwide process services Supplied Allows OpenVMS system management commands, such as SHOW USERS, SHOW SYSTEM, and STOP/ID=, to operate clusterwide.
Availability Manager Supplied From either an OpenVMS system or a Windows node, enables you to monitor one or more OpenVMS nodes on an extended LAN or wide area network (WAN). That is, the nodes for which you are collecting the information must be in the same extended LAN and there should be an interface that communicates with the collector nodes as well as the WAN analyzer. The Availability Manager collects system and process data from multiple OpenVMS nodes simultaneously, and then analyzes the data and displays the output using a native Java GUI.
HP WBEM Services for OpenVMS Supplied WBEM (Web-Based Enterprise Management) enables management applications to retrieve system information and request system operations wherever and whenever required. It allows customers to manage their systems consistently across multiple platforms and operating systems, providing integrated solutions that optimize your infrastructure for greater operational efficiency.
SCACP (Systems Communications Architecture Control Program) Supplied Enables you to monitor, manage, and diagnose cluster communications and cluster interconnects.
DNS (Distributed Name Service) Optional Configures certain network nodes as name servers that associate objects with network names.
LATCP (Local Area Transport Control Program) Supplied Provides the function to control and obtain information from LAT port driver.
LANCP (LAN Control Program) Supplied Allows the system manager to configure and control the LAN software on OpenVMS systems.
NCP (Network Control Protocol) utility Optional Allows the system manager to supply and access information about the DECnet for OpenVMS (Phase IV) network from a configuration database.
NCL (Network Control Language) utility Optional Allows the system manager to supply and access information about the DECnet--Plus network from a configuration database.
POLYCENTER Software Installation Utility (PCSI) Supplied Provides rapid installations of software products.
Queue Manager Supplied Uses OpenVMS Cluster generic and execution queues to feed node-specific queues across the cluster.
Show Cluster utility Supplied Monitors activity and performance in an OpenVMS Cluster configuration, then collects and sends information about that activity to a terminal or other output device.
SDA (System Dump Analyzer) Supplied Allows you to inspect the contents of memory saved in the dump taken at crash time or as it exists in a running system. You can use SDA interactively or in batch mode.
SYSMAN (System Management utility) Supplied Enables device and processor control commands to take effect across an OpenVMS Cluster.
VMSINSTAL Supplied Provides software installations.
AUTOGEN utility Supplied Optimizes system parameter settings based on usage.
Monitor utility Supplied Provides basic performance data.
Authorize utility Supplied Modifies user account profiles.
SET ACL command Supplied Sets complex protection on many system objects.
SET AUDIT command Supplied Facilitates tracking of sensitive system objects.
Storage management
Backup utility Supplied Allows OpenVMS Cluster system managers to create backup copies of files and directories from storage media and then restore them. This utility can be used on one node to back up data stored on disks throughout the OpenVMS Cluster system.
Mount utility Supplied Enables a disk or tape volume for processing by one computer, a subset of OpenVMS Cluster computers, or all OpenVMS Cluster computers.
Volume Shadowing for OpenVMS Optional Replicates disk data across multiple disks to help OpenVMS Cluster systems survive disk failures.

1.5.3 System Management Tools from OpenVMS Partners

OpenVMS Partners offer a wide selection of tools to meet diverse system management needs. The types of tools are described in the following list:

  • Schedule managers
    Enable specific actions to be triggered at determined times, including repetitive and periodic activities, such as nightly backups.
  • Event managers
    Monitor a system and report occurrences and events that may require an action or that may indicate a critical or alarming situation, such as low memory or an attempted security breaking.
  • Console managers
    Enable a remote connection to and emulation of a system console so that system messages can be displayed and commands can be issued.
  • Performance managers
    Monitor system performance by collecting and analyzing data to allow proper tailoring and configuration of system resources. Performance managers might also collect historical data for capacity planning.

For information about OpenVMS Partners and the tools they provide, see the OpenVMS System Management website:


1.5.4 Other Configuration Aids

In addition to these utilities and partner products, several commands are available that allow the system manager to set parameters on Fibre Channel, SCSI and SAS storage subsystems to help configure and manage the system. See the appropriate hardware documentation for more information.

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