Transfer rate .

• transfer rate

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DVD - Transfer rates

1 Read and write speeds for the first DVD drives and players were of

1,385 kB/s (1,353 KiB/s); this speed is usually called "1×". More recent models, at 18× or 20×, have 18 or

20 times that speed. Note that for CD drives, 1× means 153.6 kB/s (150 KiB/s), about one-ninth as swift.


CD-ROM - Transfer rates

1 If a CD-ROM is read at the same rotational speed as an audio CD, the

data transfer rate is 150 KiB/s, commonly referred to as "1×"



1 As of 2004, the fastest transfer rate commonly available is about 52× or 10,400

rpm and 7.62 MiB/s



1 Faster 12× drives were common beginning in

early 1997



1 Problems with vibration, owing to limits on achievable symmetry and strength in mass-produced media, mean that CD-ROM drive speeds

have not massively increased since the late 1990s



1 Additionally, with a 700 MB CD-ROM fully readable in under 2½ minutes at 52× CAV, increases in actual data transfer

rate are decreasingly influential on overall effective drive speed when taken into consideration with other factors such as loading/unloading, media recognition,

spin up/down and random seek times, making for much decreased returns on

development investment



1 CD-Recordable drives are often sold with three different speed ratings, one speed for

write-once operations, one for re-write operations, and one for read-only

operations. The speeds are typically listed in that order; i.e. a 12×/10×/32× CD drive

can, CPU and media permitting, write to CD-R discs at 12× speed (1.76 MiB/s), write to

CD-RW discs at 10× speed (1.46 MiB/s), and read from CDs at 32× speed (4.69 MiB/s).



1 72× 6,750–10,800 up to 88.4736 up to 10.5 2,000

(multi-beam)


Hard disk drive - Data transfer rate

1 Transfer rate can be influenced by file system fragmentation and the layout of the files.


Hard disk drive - Data transfer rate

1 Since data transfer rate performance only tracks one of the two

components of areal density, its performance improves at a lower

rate.


Bit rate - Goodput (data transfer rate)

1 Goodput or data transfer rate refers to the achieved average net bit rate that is

delivered to the application layer, exclusive of all protocol overhead, data packets

retransmissions, etc. For example, in the case of file transfer, the goodput

corresponds to the achieved file transfer rate. The file transfer rate in bit/s can be

calculated as the file size (in bytes), divided by the file transfer time (in seconds), and

multiplied by eight.https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 As an example, the goodput or data transfer rate of a V.92 voiceband modem is affected by the modem physical layer and data link layer protocols. It is sometimes higher

than the physical layer data rate due to V.44 data compression, and

sometimes lower due to bit-errors and automatic repeat request

retransmissions.https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 If no data compression is provided by the network equipment or protocols,

we have the following relation:



1 Goodput ≤ Throughput ≤ Maximum throughput

≤ Net bit rate



1 for a certain communication path.


Parallel ATA - ATA standards versions, transfer rates, and features

1 Note that the transfer rate for each mode (for example, 66.7 MB/s for

UDMA4, commonly called "Ultra-DMA 66", defined by ATA-5) gives its

maximum theoretical transfer rate on the cable



1 Congestion on the host bus to which the ATA adapter is attached may also

limit the maximum burst transfer rate. For example, the maximum

data transfer rate for conventional PCI bus is 133 MB/s, and this is

shared among all active devices on the bus.



1 Hard drive performance under most workloads is limited first and second

by those two factors; the transfer rate on the bus is a distant third in

importance



1 As of April 2010 mechanical hard disk drives can transfer data at up to

157 MB/s, which is beyond the capabilities of the PATA/133

specification. High-performance solid state drives can transfer data at up

to 308 MB/s.



1 Only the Ultra DMA modes use CRC to detect errors in data transfer

between the controller and drive. This is a 16 bit CRC, and it is used for

data blocks only. Transmission of command and status blocks do not use the fast signaling methods that

would necessitate CRC. For comparison, in Serial ATA, 32 bit CRC is used for both commands and data.


Hard drive - Data transfer rate

1 Transfer rate can be influenced by file system fragmentation and the layout of the files.


Data transfer rate (disk drive)

1 These performance characteristics can be grouped into two categories:

#Access time|access time and #Data transfer rate|data transfer time (or

rate).


Data transfer rate (disk drive) - Access time

1 The access time or response time of a rotating drive is a measure of the time it takes before the drive can

actually Data transmission|transfer data


Data transfer rate (disk drive) - Seek time

1 With rotating drives, the seek time measures the time it takes the head

assembly on the actuator arm to travel to the track of the disk where

the data will be read or written



1 A rotating drive's average seek time is the average of all possible seek

times which technically is the time to do all possible seeks divided by the number of all possible seeks, but in

practice it is determined by statistical methods or simply

approximated as the time of a seek over one-third of the number of

trackshttps://store.theartofservice.com/the-transfer-rate-toolkit.html


1 The first HDD had an average seek time of about 600 ms, and by the middle 1970s, HDDs were available with seek times of

about 25ms. Some early PC drives used a stepper motor to move the heads, and as a result had seek times as slow as 80–120ms, but this was quickly improved by voice coil type actuation in the 1980s, reducing seek

times to around 20ms. Seek time has continued to improve slowly over time.



1 The other two less commonly referenced seek measurements are track-to-track and full stroke. The track-to-track measurement is the

time required to move from one track to an adjacent track. This is the

shortest (fastest) possible seek time. In HDDs this is typically between 0.2

and 0.8ms. The full stroke measurement is the time required to

move from the outermost track to the innermost track. This is the

longest (slowest) possible seek time.



1 With SSDs there are no moving parts, so a measurement of the seek time

is only testing electronic circuits preparing a particular location on the

memory in the storage device. Typical SSDs will have a seek time

between 0.08 and 0.16ms.


Data transfer rate (disk drive) - Short stroking

1 Short stroking is a term used in enterprise storage environments to describe an HDD that is purposely restricted in total capacity so that the actuator only has to move the heads across a smaller number of

total tracks


Data transfer rate (disk drive) - Effect of audible noise and vibration control

1 Measured in A-weighting|dBA, audible noise is significant for certain applications, such as

digital video recorder|DVRs, digital audio recording and quiet PC|quiet computers. Low

noise disks typically use fluid bearings, slower rotational speeds (usually 5,400rpm)

and reduce the seek speed under load (Automatic Acoustic Management|AAM) to

reduce audible clicks and crunching sounds. Drives in smaller form factors (e.g. 2.5inch)

are often quieter than larger drives.


Data transfer rate (disk drive) - Effect of audible noise and vibration control

1 Some desktop- and laptop-class disk drives allow the user to make a

trade-off between seek performance and drive noise


Data transfer rate (disk drive) - Rotational latency

1 Rotational latency (sometimes called rotational delay or just latency) is the delay waiting for the rotation of the disk to bring the required disk sector

under the read-write head



1 The spindle motor speed can use one of two types of disk rotation

methods: 1) constant linear velocity (CLV), used mainly in optical storage,

varies the rotational speed of the optical disc depending upon the

position of the head, and 2) constant angular velocity (CAV), used in HDDs,

standard FDDs, a few optical disc systems, and Gramophone record|

vinyl audio records, spins the media at one constant speed regardless of

where the head is positioned.



1 In both these schemes contiguous bit transfer rates

are constant


Data transfer rate (disk drive) - Effect of reduced power consumption

1 Power consumption has become increasingly important, not only in mobile devices such as laptops but also in server and desktop markets


Data transfer rate (disk drive) - Other

1 The or command overhead is the time it takes for the drive electronics

to set up the necessary communication between the various components in the device so it can read or write the data. This is in the

range of 0.003Millisecond|ms. With a value this low most people or

benchmarks tend to ignore this time.


Data transfer rate (disk drive) - Other

1 The measures the time it takes the heads to settle on the target track

and stop vibrating so it does not read or write off track. This amount is

usually very small (typically less than 0.1 ms) or already included in the seek time specifications from the

drive manufacturer. In a benchmark test the settle time would be

included in the seek time.https://store.theartofservice.com/the-transfer-rate-toolkit.html

Data transfer rate (disk drive) - Data transfer rate

1 The sustained data transfer rate or sustained throughput of a drive will

be the slower of the sustained internal and sustained external rates



1 ; Media rate: Rate at which the drive can read bits from the surface of the media.



1 ; Sector overhead time: Additional time (bytes between sectors) needed

for control structures and other information necessary to manage the

drive, locate and validate data and perform other support functions.



1 ; Head switch time: Additional time required to electrically switch from

one head to another and begin reading; only applies to multi-head

drive and is about 1 to 2 ms.



1 ; Cylinder switch time: Additional time required to move to the first

track of the next cylinder and begin reading; the name cylinder is used because typically all the tracks of a drive with more than one head or

data surface are read before moving the actuator. This time is typically

about twice the track-to-track seek time. As of 2001, it was about 2 to 3

ms.https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 *, a typical 7200RPM desktop HDD has a disk-to-disk buffer|buffer data transfer rate up to 1030Mbit/s. This rate depends on the track location,

so it will be higher on the outer zones (where there are more data sectors per track) and lower on the inner

zones (where there are fewer data sectors per track); and is generally somewhat higher for 10,000RPM

drives. https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 *Floppy disk drives have sustained disk-to-disk buffer|buffer data

transfer rates that are one or two orders of magnitude slower than that

of HDDs.



1 *The sustained disk-to-disk buffer|buffer data transfer rates varies amongst families of Optical disk

drives with the slowest CD-ROM#Transfer rates|1x CDs at

1.23Mbit/s floppy-like while a high performance Blu-ray disc#Recording

speed|12x Blu-ray disc drive at 432Mbit/s approaches the

performance of HDDs.https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 A current widely used standard for the buffer-to-computer interface is

3.0Gbit/s SATA, which can send about 300megabyte/s (10-bit encoding)

from the buffer to the computer, and thus is still comfortably ahead of

today's disk-to-buffer transfer rates.


Data transfer rate (disk drive) - Effect of file system

1 Transfer rate can be influenced by file system fragmentation and the

layout of the files. Defragmentation is a procedure used to minimize

delay in retrieving data by moving related items to physically proximate

areas on the disk. Some computer operating systems perform

defragmentation automatically. Although automatic defragmentation is intended to reduce access delays,

the procedure can slow response when performed while the computer

is in use.


Data transfer rate (disk drive) - Effect of file system

1 Flash memory-based SSDs do not need defragmentation; however

because SSDs write pages of data that are much larger than the blocks of data managed by the file system,

over time, an SSD's write performance can degrade as the

drive becomes full of partial pages and/or pages no longer needed by

the file systemhttps://store.theartofservice.com/the-transfer-rate-toolkit.html

Data transfer rate (disk drive) - Effect of areal density

1 Simply increasing the number of tracks on a disk can affect seek times but not gross

transfer rates


Data transfer rate (disk drive) - Interleave

1 Sector interleave is a mostly obsolete device characteristic related to data rate, dating back to when computers

were too slow to be able to read large continuous streams of data



1 However, because interleaving introduces intentional physical delays

between blocks of data thereby lowering the data rate, setting the interleave to a ratio higher than

required causes unnecessary delays for equipment that has the

performance needed to read sectors more quickly. The interleaving ratio was therefore usually chosen by the

end-user to suit their particular computer system's performance

capabilities when the drive was first installed in their system.



1 Modern technology is capable of reading data as fast as it can be

obtained from the spinning platters, so hard drives usually have a fixed sector interleave ratio of 1:1, which is effectively no interleaving being

used.


Data transfer rate (disk drive) - Power consumption

1 Power consumption has become increasingly important, not only in mobile devices such as laptops but also in server and desktop markets



1 Drives use more power, briefly, when starting up (spin-up). Although this

has little direct effect on total energy consumption, the maximum power demanded from the power supply,

and hence its required rating, can be reduced in systems with several

drives by controlling when they spin up.



1 * On SCSI hard disk drives, the SCSI controller can directly control spin up

and spin down of the drives.



1 * Some Parallel ATA (PATA) and Serial ATA (SATA) hard disk drives support power-up in standby or PUIS: each

drive does not spin up until the controller or system BIOS issues a specific command to do so. This allows the system to be set up to

stagger disk start-up and limit maximum power demand at switch-

on.https://store.theartofservice.com/the-transfer-rate-toolkit.html


1 * Some SATA II and later hard disk drives support Staggered spinup|staggered spin-up, allowing the

computer to spin up the drives in sequence to reduce load on the

power supply when booting.



1 Most hard disk drives today support some form of power management which uses a number of specific

power modes that save energy by reducing performance. When

implemented an HDD will change between a full power mode to one or

more power saving modes as a function of drive usage. Recovery from the deepest mode, typically called Sleep, may take as long as

several seconds.


Data transfer rate (disk drive) - Shock resistance

1 Shock resistance is especially important for mobile devices. Some

laptops now include active hard drive protection that parks the disk heads if the machine is dropped, hopefully before impact, to offer the greatest possible chance of survival in such

an event. Maximum shock tolerance to date is 350 Gravitational

acceleration|g for operating and 1,000 g for non-operating.


CD-ROM XA - Transfer rates

1 If a CD-ROM is read at the same rotational speed as an Compact Disc

Digital Audio|audio CD, the data transfer rate is 150KiB/s, commonly

referred to as 1×



1 In CAV mode the × number denotes the transfer rate at the outer edge of

the disc, where it is a maximum.



1 As of 2004, the fastest transfer rate commonly available is about 52× or 10,400

rpm and 7.62MiB/s



1 Problems with vibration, owing to limits on achievable symmetry and strength in mass-produced media, mean that CD-ROM drive speeds

have not massively increased since the late 1990s



1 Additionally, with a 700MB CD-ROM fully readable in under 2½ minutes at

52× CAV, increases in actual data transfer rate are decreasingly

influential on overall effective drive speed when taken into consideration

with other factors such as loading/unloading, media

recognition, spin up/down and random seek times, making for much decreased returns on development

investment


Dual layer - Transfer rates

1 Read and write speeds for the first DVD drives and players were of

1,385kilobyte|kB/s (1,353kibibyte|KiB/s); this speed is usually called 1×. More recent models, at 18× or

20×, have 18 or 20 times that speed. Note that for CD drives, 1× means 153.6kB/s (150KiB/s), about one-

ninth as swift.


Dual layer - Transfer rates

1 [http://www.loc.gov/preservation/resources/rt/

NIST_LC_OpticalDiscLongevity.pdf Final Report: NIST/Library of

Congress (LC) Optical Disc Longevity Study], September 2007 (table

derived from figure 7)


Hard disk drives - Data transfer rate

1 Since data transfer rate performance only tracks one of the two

components of areal density, its performance improves at a lower

rate.


AT Attachment - ATA standards versions, transfer rates, and features

1 Note that the transfer rate for each mode (for example, 66.7MB/s for

UDMA4, commonly called Ultra-DMA 66, defined by ATA-5) gives its

maximum theoretical transfer rate on the cable



1 Hard drive performance under most workloads is limited first and second

by those two factors; the transfer rate on the bus is a distant third in

importance



1 As of April 2010 mechanical hard disk drives can transfer data at up to

157MB/s, which is beyond the capabilities of the PATA/133

specification. High-performance solid state drives can transfer data at up

to 308MB/s.



1 Only the Ultra DMA modes use Cyclic redundancy check|CRC to detect errors in data transfer between the controller and drive. This is a 16 bit CRC, and it is used

for data blocks only. Transmission of command and status blocks do not use the fast signaling methods that would necessitate CRC. For comparison, in

Serial ATA, 32 bit CRC is used for both commands and data. www.serialata.org


Front side bus - Transfer rates

1 The Bandwidth (computing)|bandwidth or maximum theoretical throughput of the front-side bus is determined by the product of the

width of its data path, its Clock rate|clock frequency (cycles per second) and the number of data transfers it

performs per clock cycle. For example, a 64-bit (8-byte) wide FSB operating at a frequency of 100MHz that performs 4 transfers per cycle

has a bandwidth of 3200 megabytes per second (MB/s):



1 The number of transfers per Cycles per instruction|clock cycle depends

on the technology used. For example, GTL+ performs 1 transfer/cycle, EV6

2 transfers/cycle, and AGTL+ 4 transfers/cycle. Intel calls the

technique of four transfers per cycle Quad Data Rate|Quad Pumping.



1 Many manufacturers publish the frequency of the front-side bus in

MHz, but marketing materials often list the theoretical effective signaling

rate (which is commonly called Transfer (computing)|megatransfers

per second or MT/s)



1 The specifications of several generations of popular processors are indicated below.


Transfer rate

1 In telecommunications and computing, 'bit rate' (sometimes

written 'bitrate' or as a variable R) is the number of bits that are conveyed

or processed per unit of time.


Transfer rate

1 The bit rate is :wiktionary:quantified|quantified using the Data rate units|bits per

second unit (symbol 'bit/s'), often in conjunction with an SI prefix such as kilo- (1 kbit/s = 1000 bit/s), mega- (1 Mbit/s = 1000 kbit/s), giga- (1 Gbit/s = 1000 Mbit/s) or tera- (1 Tbit/s = 1000 Gbit/s). The non-standard

abbreviation bps is often used to replace the standard symbol bit/s, so that (for example) 1 Mbps is used to mean one million bits per

second.


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