How quick please to USB 2.0

Imaging a 12 GB C: Partition ( which compresses to a 7GB .tib under Normal compression ) to a new Maxtor Ext HD , spec USB 2.0 , with appropriate USB cable . Transmission speed supposedley up to 480 Mbps. Image taking 20 minutes ?

My system is a new Dell 5100 3.2ghz HT.

Am getting confused now re my mega-bits and mega-bytes etc.
Suspect I'm imaging at 1.1 rate ?

My Maxtor diags say unit working ok . Any help would be much appreciated. Thank you in advance.
ken




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If your data is a full TRUE 12 GB, that's a total of 12 x 1024 x 1024 x 1024 = 12,884,901,888 BYTES, and that is 12,884,901,888 x 8 = 103,079,215,104 BITS. Note that drive manufacturers use a convention more favorable for themselves which says that 12 GB is simply 12,000,000,000 BYTES.

If backing up that 12 GB of data took 20 minutes, that would be a rate of 103,079,215,104 / 20 / 60 / 1,000,000 = 85.9 Mbps. Notice that when we start talking about data transfer speeds, particularly in BITS, the convention is usually to use the plain English version of MEGA which would mean simply 1,000,000 , NOT the 1024 x 1024 = 1,048,576 version of MEGA.

So, your hypothetical 85.9 Mbps can now be compared to the 480 Mbps theoretical speed for USB 2.0 data transfers, and you have a rate then that is about 1/6th of the theoretical rate.

That actually may not be too shabby. Hardly anybody will actually ever achieve that full 480 Mbps transfer speed because there are just too many links in the chain getting from your hard drive to the external hard drive, each of which can impose a bottleneck to cut down on the 480 Mbps, either in terms of each link's inherent capability or because your data transfer has to compete with other ongoing operations for bus priority.

What's really a lot more useful is to compare your transfer rate with similar other software running on similar other hardware combinations in a systematic fashion.

Based on my OWN personal experience with a 6 year old DELL with a 1 GHz CPU, 100MHz motherboard, an image of 12 GB from one of my hard drives, say my 250 GB SATA hard drive, going to one of my USB 2 external hard drives in 20 minutes seems perfectly normal -- about 10 MB per second is around what I would expect. (certainly my hardware is less capable than yours -- but that's all I can offer for comparison.)

Hope that helps more than confuses.

 

Thank you so much crofttk . Very targetted and much appreciated.

It would perhaps be interesting to get a sense of a median.

My system Dell Dimension 5100 , 3.2ghz,using TI 8.0 Build 937. All other operations/progs shut down whilst imaging.

Anyone want to share their approx timings ?

ken




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my observation: it is heavily depending on from where you run TI:

A full backup of 40GB of data to my external USB2 drive, using standard compression, takes approximately:

2 hrs from the Acronis/Linux boot CD
1 hr from the WIN XP installed program
1/2 hr from the Bart PE CD Acronis plugin

so, if you've not done it already, you might want to get yourself a BartPE CD and give it a try.

Verification takes nearly the same amount of time once again.

Cheers: Othmar

 

Hmmm... Thanks. I've really got to check that out !

 

I just got a Maxtor 200GB drive and put it in a USB case. 100GB drive c:, but actual backup data was 8GB. At normal compression (from withiin Windows), it was about 6 minutes. I was pretty happy for that USB speed. When done through the Boot CD, it took about 30 minutes....

It was in a Compaq something or other with a Celeron 2.8Ghz chip... and 512 RAM

 

ken here again.
Appreciating feedback.
Just to clarify, I image the main C: partition which includes mainly Programs with little actual data. I have 512MB RAM. ATI Video Card with own 250MB memory .
thanks again all.