Glossary of Western Digital Hard Disk Drive (Letter U)

Ultra ATA
A high-speed host data transfer feature that transfers data at up to 133 MB per second. See also Ultra DMA.

Ultra DMA
A protocol for transferring data between a hard drive through the bus to the computer’s RAM. Also known as Ultra ATA, Ultra ATA/66, Ultra ATA/100, and Ultra ATA/133.

Ultra/150 CQ
A technology that optimizes the sequence of data transfers from the host to the hard drive, providing increased data transfer efficiency and resulting in higher performance for enterprise applications.

uncorrectable error
An error that cannot be overcome using error detection and correction.

unformatted capacity
The total number of usable bytes on a disk, including the space that is required to record location, boundary definitions, and servo data. See also formatted capacity.

unrecoverable error
A read error that cannot be overcome by an ECC scheme or by re-reading data when host retries are enabled.

untagged queuing
The ability of a drive to receive a maximum of one input/output (I/O) process from each initiator.

In hard drives, the replacement of a hard drive with one offering greater capacity or performance or both.

Universal Plug n Play. A set of computer network protocols that simplify the implementation of networks in the home by allowing devices to connect seamlessly. See also protocol.

UPnP NAT traversal
Combines UPnP and NAT features.

Uninterruptable Power Supply. A standalone device that provides secondary power to connected equipment in the event of a power failure.

Universal serial bus. A serial bus for connecting peripherals to a microcomputer. It connects external drives, printers, modems, mice, keyboards, etc., through a single, general-purpose port. It can automatically add and configure new devices without having to shut down and restart the system.

USB 2.0
Hi-Speed USB (USB 2.0) supports data transfer rates up to 480Mb/s. USB 2.0 is backward-compatible with USB 1.1. If you connect to a USB 1.1 device, data is transferred at USB 1.1 speed (up to 1.1 Mb/s).

USB 3.0
SuperSpeed USB (USB 3.0) supports data transfer rates of up to 5 Gb/s. USB 3.0 is backward-compatible with USB 2.0. If you connect to a USB 2.0 device, data is transferred at USB 2.0 speed (up to 480 Mb/s).

USB 3.0 HBA adapter
WD’s USB 3.0 PCI adapter card. Allows users to upgrade their PC to take advantage of the faster data transfer speeds available through the SuperSpeed USB 3.0 port.