Document revision date: 19 July 1999

target disk: In VMSINSTAL.COM or VMSKITBLD.COM, the disk to which you move the system files. Compare with source disk.

terminal queue: A type of output execution queue that uses a symbiont to direct output to a terminal printer. Compare with printer queue and server queue.

terminal servers: Communication devices dedicated for connecting terminals, modems, or printers to a local area network (LAN) and to other systems within a LAN. See also LAT protocol.

time differential factor (TDF): Difference between local system time and Coordinated Universal Time (UTC). See also Coordinated Universal Time.

track: On a disk, the collection of sectors (or blocks, on Files-11 volumes) at a single radius on one recording surface of the disk. It is accessible to a given read/write head position on the disk device.

trailer labels: On magnetic tape, labels similar to header labels, but which are written following the file.

transaction group: A group of computers involved in DECdtm transactions whose SCSNODE names must obey specific rules.

transaction log: A file that stores information about DECdtm transactions performed on a node. It is of file type .LM$JOURNAL.

trusted logical names: Logical names associated with executive mode or kernel mode.

tuning: The process of altering various system values to obtain the optimum overall performance possible from any given configuration and work load.

UAF: See user authorization file (UAF).

UETP (User Environment Test Package): A software package designed to test whether the OpenVMS operating system is installed correctly.

UIC: See user identification code (UIC).

UIC-based protection: A protection mechanism based on the user identification code (UIC) and applied to all protected objects. Compare with access control list (ACL).

update procedure: Procedure used if you have a previous version of the operating system and you want to make minor fixes to it. When you update the operating system, the update procedure replaces some system files.

upgrade procedure: If you are already running a standard version of the operating system, you can use the upgrade procedure to obtain a higher version.

user authorization file (UAF): A file containing an entry for every user that you authorize to gain access to the system. Each entry identifies the user name, password, default account, UIC (user identification code), quotas, limits, and privileges assigned to individuals who use the system.

User Environment Test Package (UETP): See UETP.

user identification code (UIC): The pair of numbers assigned to users, files, and other system objects, that specify the type of access available to the owner, group, world, and system. The UIC consists of a group number and a member number separated by a comma and enclosed within square brackets. Same as UIC. See also account and UIC-based protection.

user mode: The least privileged processor access mode. User processes and run-time library routines run in user mode.

UTC: See Coordinated Universal Time.

utility program: A program supplied by Compaq that performs a set of related operations. For example, the Backup utility (BACKUP) allows you to save and restore files.

VAXcluster satellite: In a Local Area VAXcluster configuration, a VAXcluster computer without a local system disk. A VAXcluster satellite uses disks and tapes locally connected to a VAXcluster server.

VAXcluster server: In a Local Area VAXcluster configuration, a VAXcluster node that uses the mass storage control protocol (MSCP) server and tape mass storage control protocol (TMSCP) server software to make its locally connected disks and tapes available to VAXcluster satellites over the local area network (LAN).

VAXcluster system: A loosely coupled configuration of two or more VAX computers and storage subsystems. A VAXcluster system appears as a single system to the user, even though it shares some or all of the system resources. When a group of VAX computers shares resources in a VAXcluster environment, the storage and computing resources of all the computers are combined, which can increase the processing power. See also OpenVMS Cluster system.

VAXport drivers: In a VAXcluster environment, device drivers that control the communication paths between local and remote ports. (Examples are PADRIVER for the CI, PEDRIVER for the LAN, and PIDRIVER for the DSSI.)

vector: On VAX systems, a group of related scalar values, or elements, all of the same data type.

vector-capable systems: On VAX systems, those systems that comply with the VAX vector architecture.

vector consumer: On VAX systems, a process requiring the vector capability and having a vector context.

vector-present processor: On VAX systems, an integrated scalar-vector processor pair, included in a VAX vector processing system configuration.

virtual device server: Serves physical device media and sets of logical disk blocks to client systems in a local area network (LAN). Systems running the appropriate client software can connect to virtual devices as though they are locally attached devices. A virtual device server does not impose a file system on the virtual devices that it serves. See also InfoServer system.

virtual device unit: With an InfoServer system, a virtual device that represents the local OpenVMS context for a volume that resides on a remote server.

Virtual disk units have a device name in the DADn: format. Virtual tape units have a device name in the MADn: format.

See also binding, InfoServer system, and virtual device server.

volatile database: On a node in a network, a working copy of the DECnet configuration database that reflects current network conditions. Contrast with permanent database.

volume: Disk or tape media that has been prepared for use by creating a new file structure on it and mounting it on a device.

volume set: A collection of disk volumes bound into a single entity by the DCL command MOUNT/BIND. To users, a volume set looks like a single, large volume.

Also, the volumes on which a set of multivolume files is recorded.

volume space: Set of all logical sectors on a volume containing information about the volume.

writable image: A known image for which a shared non-copy-on-reference writable section is removed from physical memory (for paging reasons or because no processes are referencing it), and it is written back to the image file.

write lock: A device becomes write-locked when a hardware or user error occurs while a disk or magnetic tape volume is mounted for a write operation. For example, if a disk is write-locked or a tape is missing a write ring, the hardware generates an error.

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