June 3rd, 2010, 04:05 PM #1
Data transfer rates
I have a couple new hard drives that are hooked together with firewire 800 cables.
I copied about 90G of files from one hard drive to the other.
At 800Mb/s it should take a couple minutes, right?
It took 35 minutes, which is about 45Mb/s.
Anyone know why the transfer rate was nowhere near 800Mb/s?
Last edited by Bogey; June 3rd, 2010 at 05:27 PM.
June 3rd, 2010, 05:59 PM #2
June 3rd, 2010, 06:21 PM #3
Originally Posted by dabeechman
June 3rd, 2010, 07:01 PM #4
Ah, that is where my expertise runs out. There were some PC bugs that would cause a situation like this, but I am not familiar with Macs. Sorry 'bout that.
June 3rd, 2010, 07:08 PM #5
After a little investigating, here's what I learned.
I'm transferring ~90M bytes.
The firewire 800 transfers at ~800M bits per second.
8 bits per byte, divide by ten, it should run ~80M bytes per second.
It's still around half as fast as it should be at ~45M bytes per second.
June 4th, 2010, 01:36 AM #6
actually divide by 8 not 10
most likely the hard drive is not fast enough to write data at that speed
the problem with computer equipment is that it will run as fast as its slowest piece of hardware, if your drives can only write data at 45MB/s
It won't matter what the speed of your connector is it wouldn't write any faster than 45MB/s
it is like back in the day when GB network cards first came out the system could be connected at 1GB/s but the buss system of the computer operated at 33MB/s well the data will get downloaded no faster than 33MB/s.
if your hard drives were 15KRPM drives (Spindle speed) it will transfer a lot faster. I am guessing you have 7200RPM drives but sicne the fastest external drives are 7200 maybe 10K now you won't copy data any faster than 45 MB/s although a larger buffer will help with speeds get used to 45MB/s
June 8th, 2010, 05:16 AM #7
Pretty much nailed it. That's a lot of data to move and it's still faster than usb. You might want to think about cloning the drive next time using something like SuperDuper. I did this for my MP3 drive a few months ago and it saved me a ton of time.
Originally Posted by RoyalPain
June 8th, 2010, 11:20 AM #8
There is another way to transfer the data and will run it a bit faster but it goes back to the good old command line way of things but with very little overhead. it will transfer a lot faster than what it did graphically. is using the "rsync" command. it is a little archaic but it works.