What is RAID, FIREWIRE, and USB Technology, an information overview

The definition of RAID: RAID is an acronym for Redundant Array of Independent Disks. RAID is a developed technology to improve data storage protection and performance while saving large amounts of data to a hard drive, without necessarily requiring improvements in disk drive technology. As the meaning and popularity of the RAID technology has grown, several RAID configurations for storing large amounts of data have been developed and standardized for use. These RAID "levels" are now commonly put to use in the industry. The simplest RAID configurations either "stripe" data across two drives to increase data transfer speed, and offer no data protection; or "mirror" (duplicate) redundant data onto a second drive, without increasing drive or system performance. There are more advanced configurations that involve three or more drives, and simultaneously provide fault tolerance, increased performance, and the ability to "recreate" information onto a spare drive should a drive failure occur. These more advanced RAID configurations are preferred in server environments where maximum data availability and performance is critical. RAID Mirroring:   Top of Page Also known as "drive mirroring", RAID 1 simultaneously copies data to a second drive. This method offers data protection and good drive performance where a mirrored drive fails. RAID 1 is the simplest RAID configuration requires only a minimum of two drives both with equal storage capacity, and the drives be added in pairs. The main disadvantage of RAID 1 is that it uses 100% drive overhead (the highest of all RAID levels), which can be considered an inefficient use of drive capacity.   What is Firewire? FireWire is a high-speed serial input/output (I/O) technology for connecting peripheral devices to a computer or to each other. It's one of the fastest peripheral standards ever developed? And now, at 800 megabits per second (Mbps), it's even faster. Based on Apple-developed technology, FireWire was adopted in 1995 as an official industry standard (IEEE 1394) for cross-platform peripheral connectivity. By providing a high-bandwidth, easy-to-use I/O technology, FireWire inspired a new generation of consumer electronics devices from many companies, including Canon, Epson, HP, Iomega, JVC, LaCie, Maxtor, Mitsubishi, Matsushita (Panasonic), Pioneer, Samsung, Sony, and Texas Instruments. Products such as DV camcorders, portable external disk drives, and MP3 players like the Apple iPod would not be as popular as they are today with- out FireWire. Data Transfer Speeds Up to 800 Mbps  Top of Page FireWire 800 is capable of transferring data at 800 Mbps. Twice the speed of the original FireWire. This performance increase has been achieved primarily by using the same highly efficient encoding scheme used by Gigabit Ethernet and Fibre Channel. In fact, the FireWire roadmap outlined in the IEEE 1394b standard will eventually take the theoretical bit rate to 1600 Mbps and then up to a staggering 3200 Mbps. That's 3.2 gigabits per second, which will make FireWire indispensable for transferring massive data files and for even the most demanding video applications, such as working with uncompressed high-definition (HD) video or multiple standard-definition (SD) video streams. Distances Up to 100 Meters Not only is FireWire 800 twice as fast as before, but it can be used over much longer distances. The 1394b specification allows the use of various types of cabling, each offering different speed/distance capabilities. Plug-and-Play Connectivity  Top of Page FireWire allows for true hot-swapping, plug-and-play connection of peripheral devices. There is no need to shut down the computer before adding or removing a FireWire device. Nor do you need to install drivers, assign unique ID numbers, or connect terminators. You can connect a few devices in a simple chain or add hubs to attach as many as 63 devices to a single FireWire bus. The number of available FireWire buses can be increased via PCI and Card Bus cards. FireWire is a true peer-to-peer technology. Using a FireWire hub, multiple computers and FireWire peripherals can be connected at the same time. Such an arrangement would, for instance, enable two computers to share a single FireWire camera. Key Features of Firewire 800 Data transfer speeds up to 800 Mbps Distances up to 100 meters Plug-and-play connectivity Highly efficient architecture Compatibility with current FireWire products Real-time data delivery On-bus power More advanced than USB 2.0 Support for a wide range of devices What is USB 2.0? The more recent motivation for USB 2.0 stems from the fact that PCs have increasingly higher performance and are capable of processing vast amounts of data. At the same time, PC peripherals have added more performance and functionality. User applications such as digital imaging demand a high performance connection between the PC and these increasingly sophisticated peripherals. USB 2.0 addresses this need by adding a third transfer rate of 480 Mb/s to the 12 Mb/s and 1.5 Mb/s originally defined for USB. USB 2.0 is a natural evolution of USB, delivering the desired bandwidth increase while preserving the original motivations for USB and maintaining full compatibility with existing peripherals. Thus, USB continues to be the answer to connectivity for the PC architecture. It is a fast, bi-directional, isochronous, low-cost, dynamically attachable serial interface that is consistent with the requirements of the PC platform of today and tomorrow. USB Functions definition:  Top of Page A function is a USB device that is able to transmit or receive data or control information over the bus. A function is typically implemented as a separate peripheral device with a cable that plugs into a port on a hub. However, a physical package may implement multiple functions and an embedded hub with a single USB cable. This is known as a compound device. A compound device appears to the host as a hub with one or more non-removable USB devices. Each function contains configuration information that describes its capabilities and resource requirements. Before a function can be used, it must be configured by the host. This configuration includes allocating USB bandwidth and selecting function-specific configuration options. Examples of functions include the following: A human interface device such as a mouse, keyboard, tablet, or game controller An imaging device such as a scanner, printer, or camera A mass storage device such as a CD-ROM drive, floppy drive, or DVD drive The entire USB 2.0 specification can be downloaded at the usb.org web site in the documents section. Top of Page