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Internal and External Hard Drives - Bottleneck?

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BrittQ

macrumors regular
Original poster
May 23, 2007
235
0
If you have an internal hard drive that is 5400rpm and an external that is 7200rpm, will the external be just as slow as the 5400? Does the speed on the internal hard drive affect the speed of the external drive?
 
I have a fw800 MyBook Pro (7200) connected and access is ... instant. I can't say whether their speeds will appear to interfere with the internal HD as mine is also 7200rpm! :D
 
BrittQ said:
If you have an internal hard drive that is 5400rpm and an external that is 7200rpm, will the external be just as slow as the 5400? Does the speed on the internal hard drive affect the speed of the external drive?
Click to expand...

1. The speed of one drive doesn't affect the speed of the other drive at all. Of course, if you copy from one drive to another, you will be limited by the slower drive.

2. RPM is not the only thing that affects speed. Another factor is the data density (a 250 GB hard drive in a MacBook will be a lot faster than a 100 GB hard drive at same RPM), and how full the hard disk is (the outer tracks of a hard drive have higher density and work faster than the inner tracks).

3. The speed of the external drive is also limited by the speed of the interface. USB 2.0 is slowest, FireWire 400MBit/s is faster. Both FireWire 800MBit/s and eSATA are fastest; both are in practice limited by the speed of the external drive.

4. Also note that you can simultaneously read from one drive and write to another drive, so copying from internal to external or the other way round is a lot faster than copying from internal to internal or external to external disk.
 
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