Last November, I received an e–mail from my editor, Tom Kenny saying “…We have a feature on network storage systems that we’re trying to figger out (so) what we’d like from you, if you agree, is a glossary of common storage and network terms. An IT glossary for the uninitiated pro audio folks. Whammy think? A whole column of pedants in a box.” So began this month’s Bitstream, a bass ackwards version of my usual offering.
Granted, I could never compete with the many excellent IT glossaries out there on the web but, I’ve tried to gather the most common TLAs, techie phrases and geek–speak for your edification. For those who need a bit of a mental housecleaning, this month will either sweep away some cobwebs or increase the BBF by several orders of magnitude!
Part One, Two, Three and Four of Pedants In A Big Box was published in March, June, July and August of 2004. Note that bold words have their own definitions in this glossary…
microcontroller —
Microcontrollers are complete computers on a chip and contain, in addition to a CPU, memory and I/O. Microcontrollers are often used by embedded systems, working transparently for the user.
mLAN —
mLAN is a well conceived, audio production–specific protocol overlay developed by Yamaha for the FireWire 1394 standard. As a proprietary protocol with licensing fees, mLAN has not enjoyed wide industry uptake.
MP3 — MPEG-1 Layer III
MP3, a Perceptual Subband/Transform Codec, is part of the groundbreaking Motion Picture Experts Group (MPEG) standard for lossy compression of audio/video data. The motion video portion of the MPEG-1 standard was itself derived from the Joint Picture Expert Group standard for lossy compression of still images.
MPEG — Motion Picture Experts Group
The Motion Picture Experts Group, an offshoot of the still image Joint Picture Experts Group (JPEG), creates and licenses standards for digital multimedia file formats and infrastructure. The MPEG is under the ISO umbrella.
MPT — Music Pictures Television
MPT refers to the three consumables, audio, video and still images, driving consumer adoption of storage and converged products.
multicast, multicasting —
Multicasting is an Ethernet addressing scheme that is used to either target specific packets at specific device types, sort of (MIDI) System Exclusive for IP, or for broadcasting to all nodes simultaneously. Multicasting is a one–to–many approach to data distribution.
name resolution —
Name resolution refers to domain name resolution, a process whereby the Domain Name System is used to map human–readable host names to their corresponding IP addresses. This is the process that’s used to map human readable web addresses, such as www.apple.com, onto its “true” address, its IP address — which is <17.112.152.32>.
NAS — Network–Attached Storage
NAS describes a standalone storage “appliance” that provides file–level access via a network connection, typically Ethernet. NAS can reduce management overhead and eliminate unreliable cabling, while increasing in-band traffic.
network —
A network is two or more computers connected so as to pass data, metadata, management and control messages between nodes.
NFS — Network File System
NFS is a protocol for remote disk access over a network. NFS, a de facto standard developed by Sun Microsystems, uses UDP rather than the relatively more robust TCP protocol. In some circles, NFS also stands for Nightmare File System for the alleged unreliability of early Sun networks.
NIC — Network Interface Card or Controller
A hardware interface installed in a computer that provides a physical connection to a network.
node —
A node is a logical instance of a computer attached to a network. Nodes are usually instantiated by a NIC.
OC-nn — Optical Carrier-nn
Optical Carrier designations are used by telcos to denote SONET service tiers, OC-48 is equal to 48 times 51.84 = 2488.32 megabits per second while OC-192 is fat enough to seamlessly interoperate with IP–based 10Gig Ethernet.
operating system —
An operating system is the low level software that provides a computer’s basic features and capabilities. Operating systems can be linked to specific platforms, such Mac OS on PPC, or may, like BSD Unix, be available for a wide variety of CPUs.
OSI Model —
The OSI or Open Systems Interconnect (Reference) Model is an abstract hierarchy, developed by the ISO, that provides a standardized conceptual framework for the functional components of a heterogeneous computer network. These components are a collection or “stack” of protocols arranged into 7 “layers.” Layer 1, the PHY layer, deals with the literal nuts and bolts while the top Layer 7 formalizes the “applications” that interact with the human end user.
out–of–band —
When an auxiliary signaling channel is relegated to a separate PHY so as not to rob bandwidth the primary channel, then that separation of signal paths is referred to as out–of–band communication. Out–of–band signaling is the opposite of in–band communication and both usually refers to the passage of management, control or metadata related to network resources, like SAN nodes and LAN servers.
overhead —
In IT Land, overhead refers to any service, protocol or process that requires resources in excess of those needed by default.
P2P — Peer to Peer
Peer to peer refers to a flat network hierarchy, whereby clients interact directly without the intervention of servers.
packet, to packetize —
A packet is an autonomous unit of data encapsulated by a protocol header and/or trailer. In general, the header provides network control and routing information for directing the packet through the fabric, while the trailer contains data for ensuring packets are not delivered with corrupted contents. Packetizing refers to encapsulating data into packet form.
packet switched —
A stateless network transport method whereby individual packets are routed between network nodes via a combination of packet header addressing and complex routing algorithms designed to optimize throughput. All nodes on the network are ”always on,” able to send, receive and forward packets.
PAN — Personal Area Network
A PAN is a network, typically wireless, that operates within a very small area. PAN's usually provide connectivity for miniature peripherals that someone can carry on his or her person.
parallel —
Parallel, the opposite of serial, refers to moving data in a side–by–side, simultaneous fashion, either physically or virtually, whereby each clock cycle moves or processes entire bytes of data.
PB, petabyte —
A petabyte is one thousand, 1024 actually, terabytes. A petabyte, once thought to be an absurdly large amount of data, is now not an uncommon amount of aggregate storage in the IT departments of enterprise and large entertainment companies.
PCI — Peripheral Component Interconnect
Originally an ad hoc standard introduced by Intel, PCI has become the world’s most widely adopted local bus standard. The current PCI-X 2.0 64-bit bus standard provides a compact form factor and supports signaling speeds up to 533 million transfers per second, up to 4.3 gigabytes per second of bandwidth which is 32 times faster than the first generation.
perceptual subband/transform codec —
Perceptual subband/transform codecs are codecs designed to reduce the data rate and/or size of a digital audio file. The encoder applies a psychoacoustic model to estimate whether, in any particular band of frequencies, the signal strength in that band is above or below the perceptual threshold relative to adjacent frequency bands. If the signal is above the masking threshold, a spectral coefficient or value is generated to represent the signal in that band and the coefficient becomes the stand–in or representation of the actual audio in that band. If the signal is not above the predicted masking threshold, then that band of frequencies are tossed out to reduce the final size of the essence.
To be continued…
