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Answer:

If you have the disk rotating at 360 rpm, then one byte is read off the disk in:

T = b/rN = 1/(360 rpm*512 bytes/sector * 96 sectors/track)

T = 3.4 μs

If one interrupt occurs every byte, then the operating system will process an interrupt (2.5 μs), then do some work, thenprocess another interrupt, etc. The time between interrupts is equal to the time it takes to read one byte. In other words, the disk will read one byte, theninterrupt the operating system, then read another byte. The operating system will only be able to get work done if it has enough time to finish processing aninterrupt before the next one occurs. In this case, the processor will spend 2.5 μs / 3.4 μs or 74% of its time handling I/O.

With DMA, there is only one interrupt for the entire sector. It takes 3.4 μs/byte * 512 bytes/sector = 1,741 μs to read the sector.Therefore the processor only spends 2.5 μs / 1741 μs = .14% of the time handling I/O.

Note: The above answer does not take into account rotational delay. If you include rotational delay, then the time to read a bytebecomes very large:

T = b/rN + 1/2r = 83 ms

This means the time the processor spends processing interrupts is very small (approximately .003% in both cases).

It should be clear that disk striping can improve the data transfer rate when the strip size is small compared to the i/o request size. it shouldAlso be clear that raid 0 provides improved performance relative to a single large disk, because multiple i/o requests can be handled in parallel. however,In this latter case, is disk striping necessary? that is, does disk striping improve i/o request rate performance compared to a comparable disk array withoutStriping?

Answer:

Consider a disk array that does not use striping. If multiple I/O requests are issued for files on different disks, then performanceis the same as a striped disk array. However, the advantage of striping is that it improves the chances that multiple I/O requests will in fact be for data ondifferent disks. Without striping, all the files from a given directory will be on the same disk, so a single user operating in a single directory will be usingone disk instead of all the disks in the array. Likewise, it is likely that all user files will be on one disk, and all binaries on another, so that multipleusers accessing their files will use the same disk. Disk striping is a simple, automated way for the administrator of the array to ensure that files are spreadout across all the disks.

You purchase a disk drive that spins at 9600 rpm, stores 300 kb per track, and has an average seek time of 8 ms.

  • What is the average transfer time to read a 1 MB file, assuming the file is stored on consecutive tracks?

T = Ts + 1/(2r) + b/(rN)

T = .008 + (60 s/m)(1 r)/ (2*9600 r/m) + (1 MB)(1024 KB/MB)(60 s/m)/(9600 r/m)(300 KB/r)

T = .008 s + .003125 s + .021333 s

T = 32.458 ms

  • What is the average transfer time to read a 1 MB file, assumingthat the file is stored in 10 separate locations on the disk, and each location has 100 KB of contiguous data?

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Operating systems. OpenStax CNX. Aug 13, 2009 Download for free at http://cnx.org/content/col10785/1.2
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