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Edris Kamali April 6th, 2004 07:11 PM

Video storage
 
Hi;
I am running out of space in my computer Hard Disk and know I am thinking of buying a external hard drive. I would like to know if the speed of hard disk with USB2 or Firewire is faster than an IDE hard disk.

thank you

George Ellis April 6th, 2004 07:48 PM

A Firewire or USB attached drive is an IDE drive. The external drive will usually not be faster than the internal drive unless you have an old machine (circa 1996). Go with the Firewire as Firewire is faster than USB (even though on paper, USB would be faster.) Some drives do both, which can be beneficial if you need to take it somewhere to 'share' a file as many will at least have USB.

Edris Kamali April 6th, 2004 08:06 PM

Video storage
 
Thanks George; Still I don't know how an internal HDD with transfer speed of 66mbs is faster than 480mbps speed of firewire or usb-2. Perhaps there are other factors that I am not aware of.

Rob Lohman April 7th, 2004 03:42 AM

You can roughly divide mbps or mbit/s or Mb/s by 10 to get a
rough estimate of the MB/s. So 400 mbit firewire will have a
maximum transfer speed of 40 MB/s. But I doubt you'll see those
numbers in the real world. I also doubt your harddisk will do a
sustained 66 MB/s.

In theory a firewire *connected* (which is a better word) harddisk
can definitely be slower then when the drive would've been
placed internally. In the real world I think you'll see it is also a
bit slower.

Whether that matters to you is another thing. DV is 3.6 MB/s and
I would say that you would at least need a 5 MB/s sustained
write speed to not drop any frames. Any current harddisk on a
firewire or USB 2 (make sure your computer is USB 2 as well!)
connection should capture / playback DV without any problems.

So for normal work this slightly slower speed will not be any
problem at all. If you routinely need to transfer 10+ GB from one
drive to another it might costs you some minutes.

George Ellis April 7th, 2004 06:11 AM

The confusion is you are comparing megabits to megabytes. There are 8 bits in a byte. So, Firewire is stated as 400 megabits per second. An ATA-66 drive transfers at 66 megabytes per second (theoretically), which is 528 megabits per second. Megabits is correctly listed as a little 'b' while megabytes is correctly listed as big 'B'.

Most IDE drives tend toward around a 30-40MB/s sustained transfer rate. The usual, best sustained rate for most Firewire connected drives is around 25MB/s. USB is usually closer to 20MB/s.


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