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Old 04-12-2004, 06:49 AM   #1 (permalink)
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Default What is RAID?

Hmm can anyone help me with this? I dont know what it stands for neither do I know what it does...

help me start from the scratch if possible with this please...

Thanx!
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Old 04-12-2004, 07:07 AM   #2 (permalink)
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RAID stands for "Redundant Array of Inexpensive Disks".

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.

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).

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
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Old 04-12-2004, 09:06 AM   #3 (permalink)
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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?
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Old 04-12-2004, 09:27 AM   #4 (permalink)
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Theoretically it should be half, but in reality it is not much faster at reading. The write speed or moving data is increased quite a lot using RAID -0. Doing graphics editing and working with large files with small amounts of Physical Memory (RAM) would slow systems down quite a lot without RAID -0 because they would have to access the page file frequently. With RAID-0 the page file access time would be decreased significantly.

You have to understand that the only thing that slows the CPU speed down is the RAM. CPU's can move data about at rates of 10GB/sec+, and RAM can move data about at only 400MB/sec. RAM slows the processor down, but the Hard Drives slow the RAM down.

CPU - 10GB/sec+
Memory - ~400MB/sec
Hard Drives - 133MB/sec
RAID -0 HDD's - ~250MB/sec

Even RAID -0 hard drives are still not as quick as the RAM. So in reality the more RAM you have the faster your system will be, but the information still has to travel from the HDD's to the RAM. Once the data is in the RAM the system is a lot faster. The more data your RAM can temporarily hold from the Hard Drive the better.

The least times the RAM has the access the Hard Drives the better

The RAM should get the data and hold it to make whatever you are doing faster. The more applications you open with only a limited amount of RAM the more data the RAM has to dump to make room - so that when you go back to an application you opened previously (data the RAM has dumped) the RAM has to access the hard drives again.

I blab on, but hope that helps.

Edit: Oh and don't be confused! Only RAID at mode -0 makes your system faster. RAID at mode -1 is the same speed but it makes a mirror image of all information, depending on how many HDD's are in the array.

Servers use RAID -0 and RAID -1 with hard disk arrays of 12+

They have the system accessing 6 hard drives at RAID -0 (6x 133MB/sec+) and the remainding 6 hard disks just copy the 6 RAID-0 disks.
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Old 04-12-2004, 09:32 AM   #5 (permalink)
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hmm i understand wad u mean, thx
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Old 04-12-2004, 11:41 AM   #6 (permalink)
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RAID is a bug killer.....very effective too!
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Old 04-12-2004, 01:26 PM   #7 (permalink)
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Hey Kangaroo

that was a great explination!
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Old 04-12-2004, 01:59 PM   #8 (permalink)
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Didn't even think about the PCI bus

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!
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Old 04-12-2004, 02:15 PM   #9 (permalink)
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Main problem with PC computers. Each of the parts work at speed in and of themselves.

None of the components trasfers at the same speed... Someday they will... soon they will...sooner i hope
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Old 04-12-2004, 04:09 PM   #10 (permalink)
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Quote:
Originally posted by Kangaroo

CPU - 10GB/sec+
Memory - ~400MB/sec
Hard Drives - 133MB/sec
RAID -0 HDD's - ~250MB/sec
Doesnt RAM (lets assume DDR3200) transmit around 400MB per clock cycle, not second?
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