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
The simplest RAID configurations either "stripe" data
across two drives to increase data transfer speed, and offer no
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
Also known as "drive mirroring", RAID 1 simultaneously
copies data to a second drive. This method offers
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
100% drive overhead (the highest of all RAID levels),
which can be considered an inefficient use of drive
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
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-
Data Transfer Speeds Up to 800 Mbps Top of
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
for transferring massive data files and for even the
most demanding video applications,
such as working
with uncompressed high-definition (HD) video or multiple
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
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
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
buses can be
increased via PCI and Card Bus cards.
FireWire is a true peer-to-peer technology. Using a FireWire hub,
and FireWire peripherals can be connected at the same time. Such
would, for instance, enable two computers to share a single FireWire
Key Features of Firewire 800
What is USB 2.0?
- 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
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
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:
The entire USB 2.0 specification can be downloaded at the usb.org web
site in the documents section.
- 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