Data Recording Technology & Terminology

To familiarize you with information often referred to in our website, marketing material and recording seminars, a summary of some terminology and technology information is provided. Design a data streaming, recording, playback or analysis system specific for your application by contacting a VMETRO representative near you.

Data Recording systems range from simple fibre channel loop to large switched data warehouses depending on the applicaiton requirements.

Access Time: In magnetic Disk drive, it is the time for the access arm to reach the desired track and the delay for the rotation of the disk to bring the required sector under the read-write mechanism.

Address: The ID number of a block of data in storage.

Analog recorders: Data recording systems with an A/D converter input source. The A/D converter samples the continuously varying analog signal and converts the signal into binary code for the computer.

Arbitrated Loop: In this design, all devices are in a loop or ring, similar to token ring networking. Adding or removing a device from the loop causes all activity on the loop to be interrupted. The failure of one device causes a break in the ring. Fibre Channel hubs exist to connect multiple devices together, or a simple point-to-point connection can be made. Often an arbitrated loop between two ports will negotiate to become a P2P connection, but this is not required by the standard.

Bandwidth: The transmission capacity of an electronic pathway such as a communications line, computer bus or computer channel. In a digital line, it is measured in bits per second or bytes per second. In an analog channel, bandwidth is measured in Hertz (Hz, cycles per second).

Buffer: A temporary storage area for data being transferred from one place in the computer system to another. When accessing a single sector, the controller may read the entire track and store it in a buffer.

Conduction Cooled: Cooling a board or device via a solid material, by adding a heat sink or attaching the module to the system chassis.

Conformal Coating: a coating applied to electronics equipment which provides protection in severe environment applications, including humidity resistance and other environmental contaminants. The coating improves heat dissipation of thermal radiation, increasing the efficiency of the individual heat-generating components.

Controller: Circuitry typically built into a drive that interprets signals between the host and the peripheral. It provides intelligence by acting upon the signals it receives.

Convection Cooled: Cooling a board or device via a fluid motion (typically air).

COTS/Commercial-Off-The-Shelf: is a term for software or hardware products that are ready-made and available for sale to the general public. They are often used as alternatives to in-house developments or one-off government-funded developments (GOTS). The use of COTS is being mandated across many government and business programs, as they may offer significant savings in procurement and maintenance.

cPCI/CompactPCI: An implementation of the PCI bus technology on a Eurocard form factor.

Customizable Recorders: Data recording systems which allow customer to implement specific I/O, features or unique requirements to a specific application. Source code is typically provided for the application so that additional capabilities can be added as required.

Data Striping: RAID Level 0. Refers to the segmentation of logically sequential data, such as a single file, so that segments can be written to multiple physical devices (usually disk drives) in a round-robin fashion.

Data Transfer Rate: A measure of how fast data is supplied to a peripheral or computer from the point of origin.

Diffrential:e An electrical signal configuration where information is sent simultaneously using a pair of lines in a cable. The information is interpreted by the difference in voltage between the lines. Differential interfaces allow cable lengths up to 25 meters.

Disk Drive: is a peripheral device used to read from and write to a disk.

Disk Grouping: Several disk drives that are configured to behave and appear as one device.

Disk Storage: is a group of data storage mechanisms for computers; data are transferred to planar surfaces or disks for temporary or permanent storage. Available from commercial air cooled, semi-rugged, rugged and solid-state media depending upon the environmental conditions the storage systems will be operated in.

Drive Controller: Circuitry that provides the hardware interface between the disk drive and the computer, sending and receiving signals. It interprets the computer's signals and controls the operation of the disk drive.

Fibre Channel: is a gigabit speed network technology primarily used for Storage Networking. Fibre Channel is standardized in the INCITS, an ANSI accredited standards committee. It started for use primarily in the supercomputer field, but has become the standard connection type for storage area networks in enterprise storage. Despite its name, Fibre Channel signaling can run on both twisted-pair copper wire and fiber optic cables. Fibre Channel products are available at 1 Gbit/s, 2 Gbit/s and 4 Gbit/s.

Fibre Channel Controller: A microprocessor that contains the logic and command control to oversee a Fibre Channel Storage Area Network.

Flash Memory: A form of EEPROM that allows multiple memory locations to be erased or written in one programming operation. Flash memory is non-volatile, which means that it does not need power to maintain the information stored in the chip.

FPDP/Front Panel Data Port: A platform-independent 32-bit synchronous data flow path that allows data to be transferred at high speeds (160 MB/s) over moderate distances between boards and processing blocks.

FPDP II: The next generation of FPDP that features backward compatibility with the current FPDP standard, double-edged clocking, and 400 MB/s sustained data transfer rate.

Host Adapter: connects a host system (the computer) to other network and storage devices. The terms are primarily used to refer to devices for connecting Fibre Channel drives.

JBOD/Just a Bunch Of Disks: a concatenation of disks that is not one of the numbered RAID levels, but it is a popular method for combining multiple physical disk drives into a single virtual one. As the name implies, multiple disks appear to be a single large disk. JBOD uses two or more physical drives to create one logical drive. It consists of an arry of independent disks with no redundancy.

MTBF/Mean Time Between Failure: the average time between failures of a computer or peripheral.

Optical Disk: A direct access storage device that is written and read by laser light.

PCI/Peripheral Component Interconnect: The most common I/O bus in use today. It provides a shared data path between the CPU and peripheral controllers in all kinds of computers from laptops to mainframes and embedded computers.

PCI-X/PCI eXtended: An enhanced PCI bus technology. Improves the bandwidth of PCI to more than 1GB/s.

PMC/PCI Mezzanine Card: A small and compact (74mm x 149mm) daughter card that is used extensively in VME and CompactPCI systems. Uses PCI for transfers.

Point-to-Point Topology: Two devices are connected back to back. This is the simplest topology, with limited connectivity.

Pre-Programmed Recorders: standard products that provide robust, full featured recording solutions for popular standard I/O interfaces such as FPDP/FPDP II and Serial FPDP. As standard price list items, these recorders have been fully developed, tested and documented for fast-delivery and general use.

Quick Look: a feature of some data recorders that allow a display of data as it is acquired for spot checking.

RAID/Redundant Array of Inexpensive Disks: is a system which uses multiple hard drives to share or replicate data among the drives. The multiple drives appear to the user as one large, fast drive. Depending on the version chosen, the benefit of RAID is one or more of increased data integrity, fault-tolerance, throughput or capacity compared to single drives.

RAID Controller: A microprocessor that contains the logic and command control to oversee the creation and maintenance of a RAID architecture.

Recorder: A device to record high-speed digital data using hard disks or solid state storage. The Vortex family of Open and Targeted Recorders performs high-speed streaming, digital data recording, playback and analysis.

Sealed Rotating Media/Rugged Media: disk drives in a storage unit intended for use in turbojet, turboprop or pod system requiring removable media with -40 to 60 degree C temperatures and unpressurized environments.

Sector: a sub-division of a track of magnetic hard disk or optical disk. A sector stores a fixed amount of data. The typical formatting of sectors allows holding 512 bytes (e.g. hard disks and diskettes) or 2048 bytes (e.g. optical discs) of data.

Seek Time: The time it takes a drive's read/write head to find a particular piece of data on disk. Seek time does not include latency or command overhead.

Sensor: A device that measures or detects a real-world condition, such as an acoustic (microphone, hydrophone), electromagnetic (radar) or optical (camera) signal.

Sensor I/O: The process of bringing I/O from/to a sensor into a computer or processor.

Serial FPDP/sFPDP: a high-speed low-latency serial communications protocol for use in high-speed data transfer applications, typically using a fiber optic link. The sFPDP standard supports three link speeds: 1.0625 Gbaud, 2.125 Gbaud, and 2.5 Gbaud. These three link speeds can support data transfer rates in excess of 105 MBps, 210 MBps, and 247 MBps respectively.

Shock Isolation Unit: a physical system that is used in harsh environmental applications to prevent data storage devices from interacting with its surroundings. Typically an SIU eliminates the harmful effects of shock and vibration.

Shock Rating: A rating to determine the ruggedness of a drive. Generally described by acceleration (Gs) over a given time (msec).

Solid State Media: When referring to storage, Solid State storage is implemented using integrated circuits as opposed to disk storage, using hard disks. Typical applications for Solid state media include MIL-SPEC airborne and ground vehicles, high-G, engine vibration, extended temperature, and artic/desert conditions.

Storage Area Network/SAN: is a network designed to attach computer storage devices such as disk array controllers and tape libraries to servers. SANs are common in enterprise class storage. Storage networks are distinguished from other forms of network storage by the low-level access method that they use. Data traffic on these networks is very similar to those used for internal disk drives.

Switched Fabric: All devices are connected to Fibre Channel switches, similar conceptually to modern Ethernet implementations. The switches manage the state of the fabric, providing optimized interconnections.

Temperature Control: Rugged drives can incorporate features such as built-in active thermal compensation through the use of thermal sensors, internal heaters and active cooling. The PCAs can contain specially mounted thermal sensors, providing constant temperature readings for use by the active thermal control heaters during extreme cold temperatures, with sensors providing cooling with fans for extreme high temperatures.

Track: Circular segment of a hard disk or other storage media.

Vibration (random): More closely resembles actual vibration conditions. Includes energy across the given spectrum. As described by a power spectral density (given in g squared per Hz) over a given frequency range.

Vibration (Sine on Random): Often used for a situation in which a temporary, measurable vibration (sine) is added to the constant background vibration (random).

Vibration (Sine): Mechanical oscillation of a given system. Expressed in terms of acceleration (Gs) over a specific frequency or frequency range in which the displacment follows a sine wave profile.

VME/VMEbus: An expansion bus technology, supporting up to 21 cards in a single backplane, VMEbus is widely used in industrial, telecommunications and military applications.

VXS/VME Switched Serial: A switched serial backplane fabric for VMEbus. VXS combines the existing VMEbus with enhancements to support switched fabrics.

XMC/Enhanced PMC: A small compact daughter card supporting switched serial fabrics used extensively in VME and CompactPCI systems. Can use PCI Express, parallel RapidIO, Serial RapidIO, or Hypertransport protocols.