What is RAID?

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wow... as fast as the slowest component?

hmm thats soooo unlogical... coz if u had a pentium 4 HT 3.6ghzC... wud it be as fast as the 133mhz ram u have installed?
 
you are looking at two different things.. and no it isnt un-logical..
you can onlt transmit data as fast as the slowest component..

if you are running a 3.ghz processor, YES it will process at 3.6ghz... if the bus is running at 800 MHZ.. then the speed in which the bus can transmit data, is 800 mhz... so the data has to wait its turn to be transmited to the next stop.. Now, we are talking nanoseconds here, but still latency.

it is called a bottle neck... ever hear of it... you have fat pipes and skinny pipes... all the components transmit at different speeds..

Kangaroo had a great example and i Quote
"If your CPU has an FSB speed at 333MHz (like my current CPU) but your memory has a speed of 400MHz (my current Corsair) then your CPU would simply access your memory at 333MHz.

If your CPU (333MHz) is faster than your memory (266MHz) then your FSB speed would slow down to a speed of 266MHz."

the first example the bottle neck is the cpu.. it is only 333mhz..

the second example the bottleneck is the memory...

my friend, it is VERY logical...
 
Your computer is not as slow as the slowest component in your PC. If you are playing a game the data only has to travel from your hard drive to your memory once, as soon as it is there then your RAM controls the speed of your computer.

That is why the DDR speed must equal the FSB speed (not like my computer).
 
well that depends on the game, or the movie you are watching on the DVD player, or the cd you are listening to , or the mp3 you are listening to that is being loaded by the hard drive....

all the parts have to work together ALL the time. YES the program app, song what have you runs from memory, but it has to get there somehow, and it isn't alwasy all loaded Just what is needed at the time...

Ever play a game and you get to the next level, the next level has to be loaded into memory, look at your computer, you cd light is flashing, your hard drive is spinning... the data is moving through your computer into ram.. there is latency in each one of these pieces....

how about the pagefile on your hard dive ever hear of that? that is your virtual memory, the speed in which you access it is limited to, the hard drive speed, your FSB, your processor speed, your memory speed..... all of which are running at different speeds....

that is the fundamental issue with pc's all the componets run at different speeds...

again i repeat we are talking nanoseconds here, undistinguishable by us mear humans... but very distinguishable by PC's

what about your video.. once it leave the processor, the data has to move to the video card, is AGP or PCI? how much memory on the video card? what resolution are you running?
all that will delay, or speed up the displaying of what ever you are viewing also...



i hate to say this but, one of the reasons why Most graphic artists use a MAC computer? anyone know?

all of the components on a mac are all running at the same speed, are very close, (of course RAM is runnign gthat fastest). That is why they are more efficient at working with large graphics files. that is why mac part are made with proprietary components. MAC controls all of that.


again i admit this all happens very fast, well we percive it to be very fast.. but it isn't instantaneous on your coputer. and it is limited to the slowest component on your computer...

not all the time mind you, obviously once it move from the hard drive, it speeds up on the FSB, then really speeds up when it hits memory, then hits the processor, slows down on the FSB back to the video, where it may speed up or slow down depending on if it is PCI, or AGP and if the video has it's own processing..

again we are talkign very small differences, but difference that add to inefficieny..
 
My solution to slow hard drives is to get a 4x array of SATA150 hard drives.

My solution to my computer wanting to use my page file is having 1GB+ memory :D
 
Kangaroo said:
RAID stands for "Redundant Array of Inexpensive Disks".

Reduntant array of Independant Disks

Kangaroo said:
Basically what it does is theoretically half the write time and read time. Below I will show you the difference at which non-RAID and RAID -0 ATA hard drives theoretically read and write to the hard drives.

This depends on the type of RAID-array. a mirrored set rarely has an improved write time, but can have improved readtimes due to the 2 disks being able to provide data.

Kangaroo said:
Non-RAID Read/Write

Say the hard drive was the write your username "Cheerios", and it were to do this letter by letter over time - time increases DOWN the page

Write.

C
h
e
e
r
i
o
s

See the length of your name now :) If one line were to equal a second then it would take the hard drive 8 seconds to write your name.

RAID -0 | Read/Write

Same situation but writing to 2 hard drvies simultaneously

First HDD | Second HDD
C | h
e | e
r | i
o | s

This would theoretically take half the time (4 seconds with time increasing down the page).

Not half the time, nearly half the time, cuz the RAID-controller has to calculate what's written to which disk ;)

Kangaroo said:
RAID -1 does a mirror image of you main hard drive, its the best way to back up your information - you get it twice!

Main HDD | Backup HDD (mirror)
C | C
h | h
e | e
e | e
r | r
i | i
o | o
s | s


Hope that helps. Also hope it displays correctly :) [/B]

Good explaination, except for some details.

cheerios said:
hmm i get the point but other than backing up your com, i guess it would make ur loading alot faster rite? about half the normal time?

Yeah, it increases speed a lot. During a LAN-party i noticed my "slow" Xp 1800+ loaded games & levels much faster then ppls with 2,8ghz P4's & a better VGA graphics(i had a gf4 mx 440 back then)

I had 2 40gig HDD's in a striped(=RAID-0) set, and a seprate boot disk. Using the boot disk for system and half my pagefile(windows swaps form and to is if your internal memory is full, which happens quite fast when playing games) and my raid-array
for the games and the other half of the page file.

Didn't load twice as fast, but fast enuf to grab some artillery b4 the foe does :p

Kangaroo said:
Didn't even think about the PCI bus :D

Oberjaeger is right, every component would have to be top of the range to keep up with your CPU.

But to have the fastest system I would recommend very fast RAM,
and lots of it!

No consumer level HDD makes it to 133mb/s sustained transfer. The pata bus supports up to 133mb/s, generaly, most disks don;t even make it to 30mb sustained data transfer.

Striped sets increase the sustained transfer quote a bit, but also seek actions and multiple write actions take much less time....

Kangaroo said:
The speed at which your CPU accesses your RAM is based on your FSB. If your CPU has an FSB speed at 333MHz (like my current CPU) but your memory has a speed of 400MHz (my current Corsair) then your CPU would simply access your memory at 333MHz.

If your CPU (333MHz) is faster than your memory (266MHz) then your FSB speed would slow down to a speed of 266MHz.

It is abviously a bit more complicated than above, but thats the easiest way to put it.

Not entirely true, the datatransfer across the fsb goes with 333 mhz untill the northbridge, there it's goign over on the 400mhz memory bus. The faster memory bus has to wait every 1,2 clock cycle. This gives a lot of troubles and slows down performance to even worse levels then when the ram is running @ the same speed as the fsb. Same goes for the otherway around..


asupertech said:

It is unlogical. A system with 800fsb is faster with 133mhz ram(i doubt there are 800mhz fsb mobo's supporting sdram tho)
and a 3ghz proc then with a 2.0 ghz proc.

In both cases the mem is utterly slow, but the cpu processes more data then just form the ram, also form the agp card and hdd's, which is proccesed faster by the 3ghz proc then the 2ghz one.

the slowest part is the bottle neck, but it's not soley the slowest part that sets the speed.
 
You spent such a long time picking at my post that I won't try and defend myself - except say it was a simple explaination :)

I do apologise for what I explained RAID as, Rey is correct. It was originally called Inexpensive in 1987 - but Redundant is correct.

Although RAID Level -0 is not redundant, hence does not truly fit the RAID acronym.
 
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