HPOC key terms

A running program on OpenVMS, identified by a unique process ID and owning an address space, a priority, a set of quotas, and a security profile that determines what resources it may use.

A numeric value from 0 to 31 that determines how often a process is scheduled for CPU time; higher values receive preferential treatment by the scheduler. Base priority is set at creation and can be altered by privileged users.

The maximum amount of CPU time, measured in 10-millisecond ticks, that a process may run before the scheduler considers other processes at the same priority. It is a tunable system parameter.

The collection of virtual memory pages currently resident in physical memory for a process. Its size is bounded by the process working set quota and controlled by automatic trimming and swapping.

The movement of individual virtual memory pages between physical memory and the system page file when memory is overcommitted. Page faults drive this activity and can degrade performance if excessive.

The wholesale removal of an entire process's resident pages from physical memory to the swap file when memory pressure is high or the process is idle. The process becomes ineligible to run until swapped back in.

A pair of octal numbers, [group,member], that identifies a user or resource on OpenVMS. It is used in file ownership and in protection codes to decide who may access an object.

A four-part specification (system, owner, group, world) of access rights such as read, write, execute, and delete. It is attached to files, directories, devices, and other objects to control access.

An optional list of identifiers and their allowed or denied access rights attached to a file or other object. ACLs supplement the standard protection code and allow fine-grained control for individual users or groups.

The system file, managed by the Authorize utility, that holds user accounts, their UICs, privileges, quotas, and passwords. It is the authoritative source for login validation and account attributes.

A named entity in the rights database, such as a user, a resource, or a general group, that can be granted rights and referenced in access control lists. Identifiers are the basis of OpenVMS discretionary access control.

A capability granted to a process that allows it to bypass normal security checks, such as OPER for operator functions, SYSPRV for system file access, or BYPASS for unrestricted access. Privileges may be authorized or default.

The system user authorization file that stores account records for all users, including UIC, password hash, privileges, quotas, and login flags. It is edited with the Authorize utility and read at login time.

A record in the system user authorization file that defines a login name, password, UIC, privileges, resource quotas, and restrictions for a person or service. Accounts are created and modified with the Authorize utility.

A single logical storage unit, typically one disk or one logical volume, formatted with an OpenVMS file system such as Files-11 and mounted at a drive letter-like device name. It holds files organized in directories.

Two or more disk volumes bound together so that their storage appears as one continuous file system with a single root directory. Files may span the member volumes transparently.

The act of making a volume available to the file system by validating its label and structure and attaching it to a device name. Volumes must be mounted before files on them can be accessed.

The native OpenVMS on-disk file system structure, also known as ODS (On-Disk Structure). It defines the layout of the index file, directories, and file headers used to locate and describe files.

A record in the index file that describes a file's attributes, such as owner, protection, creation time, and the locations of its data extents. Every file has at least one file header.

A contiguous range of blocks on a volume allocated to a file. A file may consist of multiple extents when contiguous space is unavailable, which can affect sequential read performance.

A named storage object managed by the logical volume manager that can span physical disks and provide redundancy or performance benefits. It presents a single device name to the file system.

A redundancy feature in which two or more volumes contain identical copies of data, so reads can be served from any member and writes go to all. It protects against disk failure and can improve read performance.

A set of OpenVMS systems connected by a common interconnect that share disks and cooperate to provide high availability. Members can fail over work and access shared storage as a single administrative domain.

The minimum number of votes that must be present in a cluster for it to remain operational. If quorum is lost, the cluster suspends activity to prevent data corruption from partitioned members.

The weighted value each cluster member contributes toward quorum. Disk devices can also hold votes, allowing a cluster to maintain quorum even when some members are unavailable.

A cluster-wide network name and address that any member can answer for, allowing clients to connect without knowing which node currently runs a service. It supports transparent failover of network services.

The transfer of a workload, such as a batch job or a network service, from a failed or shutting-down cluster member to another member so that work continues with minimal interruption.

A family of networking protocols and services originally developed by Digital, providing node addressing, task-to-task communication, and file access between systems. OpenVMS supports DECnet as an optional network transport.

A numeric identifier in DECnet that uniquely names a node on the network, historically written as area.number. It is used for routing and for addressing remote tasks and objects.

The OpenVMS product that provides Internet protocols such as TCP, UDP, IP, and application services including Telnet, FTP, and SMTP. It is configured through a menu-driven or command interface.

A record that authorizes a remote user, identified by network node and account, to access local files or accounts without a local password. Proxies are used for network file access and remote logins.

The sequence that brings OpenVMS from a halted or booting state to a running multiuser system, including loading the executive, starting the startup command procedure, and enabling logins.

The process of loading the OpenVMS operating system image from a system disk into memory and transferring control to it. Boot parameters select the root, executive, and other loadable images.

The terminal or management interface attached to a system that provides access to the boot monitor and console commands. It is used to boot the system and to observe startup messages.

The orderly process of stopping user activity, dismounting volumes, and halting the system so that data is not lost. It is normally initiated with the shutdown command and a specified time delay.

The command file, typically SYSTARTUP_VMS.COM, executed during system startup to configure devices, start queues and network services, and enable user logins. Administrators customize it for site-specific needs.

The OpenVMS BACKUP program that saves files, directories, or entire volumes to savesets and restores them later. It supports incremental, image, and physical backups and can verify written data.

The output object produced by the Backup utility, containing saved files or volume data plus a header describing the backup. Savesets may be stored on disk, magnetic tape, or other media.

A backup that saves only files changed since a previous backup, identified by a modification date or a backup journal. It reduces time and media compared with a full backup.

The operation of copying files or volume data from a saveset back to disk. Restores can recover individual files, selected directories, or an entire volume after loss or corruption.

A system file that records hardware and software error events reported by devices and the operating system. Administrators analyze it to diagnose failing components and recurring faults.