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Most of 1TB Hard disks run as 7200 RPM recently.
But why 2TB is not? Few disks have a 7200 rpm specification.
Is there a technical reason?

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Seagate Barracuda LP is actually 5900 RPM, Western Digital Caviar Green is between 5400 and 6000 RPM. There are 7200 RPM 2TB drives, like Seagate Barracuda XT, Constellation ES and Wester Digital RAID Edition 4. –  Mircea Chirea Oct 23 '10 at 15:50
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2 Answers

up vote 12 down vote accepted

It's not just a simple matter of putting a faster motor in. I think that because 2TB drives have an even higher areal density, more advanced silicon is needed to process the data at such high speeds. Also, with the increased areal density, data is physically being read faster anyway.

It looks like the 7,200rpm drives have 4 or 5 platters and were made with older technology. The new 3 platter 2TB drives step up the areal density, and slow the spindle speed. As the silicon technology advances, they will speed up to 7,200rpm again, and then add more platters to increase storage, and then increase areal density and slow down the spindles, and so on...

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So, Do 2TB hard disks have higher areal density than 1TB? How many flatters they(2TB) have? –  Benjamin Oct 23 '10 at 11:50
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platters :) -- and yea, when you think of the data density on the disk being higher, it makes sense that the speed it spins at does not need to be as great. Also it takes less power and makes less heat. –  Sirex Oct 23 '10 at 11:57
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@Benjamin: It looks like Samsung have managed to get 2TB out of 3 platters @5,400rpm, while the first Hitachi 2TB drive had 5 platters and spun at 7,200rpm. google.co.uk/… –  paradroid Oct 23 '10 at 15:23
    
Thanks jason! –  Benjamin Oct 23 '10 at 18:10
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Concerning data transfer, generally 7200 RPM drives are slightly faster; but the speed is more dependent on the other factors, i.e. sequential read, random read, sequential write, and random write speeds. Sequential read is typically the most important. Random read and sequential write are usually the second-most important.

Another important thing is the lower RPM drives last longer, use less battery power and run cooler than the higher RPM drives.

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Thanks Mehper. I think if a hard disk runs as 7200 rpm, the disk's sequential reading ability is also faster than one of 5400rpm. Did I misunderstand? –  Benjamin Oct 23 '10 at 11:44
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@Benjamin: The sequential reading ability is one of the end performance results of all the actual factors that make the drive as fast as it is. –  paradroid Oct 23 '10 at 11:46
    
@jason404 Yes it is. But I thought the most important thing to result the performance is its RPM. –  Benjamin Oct 23 '10 at 11:52
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