USB 2 problems and strange things

[Dave Neve]

Hello

I posted recently about USB 2 problems

Basically, I don't think my four ports USB 2 card is running USB 2 but USB 1
and I've tried nearly everything but without success.

I'm still trying to understand what is happening and I'd like an opion on
the following

Normally, I can make a Ghost copy of my HD1 in about 30 minutes if the copy
is sent to a second INTERNAL HD

Yesterday, Norton Ghost estimated 5 hours to send the image to my brand new
EXTERNAL hard drive (hence another reason to believe that I only have USB1)

So I made the copy as usual on an INTERNAL drive and then out of
curioisity, tried to copy the image to the EXTERNAL drive

It took only 30 minutes again!!!

No wonder I can't decide if I have USB1 or USB2

The file size is the same but sending it directly to the EXTERNAL takes much
longer than sending it by the second method.

Is this a problem of memory cache or sth?

Any ideas please?

Dave Neve

 

[Paul]

Hello

I posted recently about USB 2 problems

Basically, I don't think my four ports USB 2 card is running USB 2 but USB 1
and I've tried nearly everything but without success.

I'm still trying to understand what is happening and I'd like an opion on
the following

Normally, I can make a Ghost copy of my HD1 in about 30 minutes if the copy
is sent to a second INTERNAL HD

Yesterday, Norton Ghost estimated 5 hours to send the image to my brand new
EXTERNAL hard drive (hence another reason to believe that I only have USB1)

So I made the copy as usual on an INTERNAL drive and then out of
curioisity, tried to copy the image to the EXTERNAL drive

It took only 30 minutes again!!!

No wonder I can't decide if I have USB1 or USB2

The file size is the same but sending it directly to the EXTERNAL takes much
longer than sending it by the second method.

Is this a problem of memory cache or sth?

Any ideas please?

Dave Neve

I suspect, in the examples given here, that some methods give USB 1.1 support
and others give USB 2.0 support. I like the sound of method #4 for example.

http://www.bootdisk.com/usb.htm

I'd be looking for something that suggests EHCI support.

http://en.wikipedia.org/wiki/EHCI

 

[Dave Neve]

Hi

Thanks but this looks too difficult for my computer skills.

However, what about my original question of transfer times.

Writing the file to Internal drive takes 30 mins and to external drive 5
hours

But transfering the file from Internal to External takes only 30 mins.

The file is the same size of course in both circumstances

thanks

Dave

 

[Paul]

Hi

Thanks but this looks too difficult for my computer skills.

However, what about my original question of transfer times.

Writing the file to Internal drive takes 30 mins and to external drive 5
hours

But transfering the file from Internal to External takes only 30 mins.

The file is the same size of course in both circumstances

thanks

Dave

When something like this happens, I'd look for whether the USB device
is using a USB 1.1 driver or a USB 2.0 driver. You may look at the
480Mbit/sec versus 12Mbit/sec numbers, and conclude that the performance
ratio should be 40:1, but in practice those rates won't be achieved
due to overhead. The very best USB enclosures I've heard of, do about
35MB/sec, and a lot of other ones do somewhere in the 20-30MB/sec
range. When operated in USB 1.1 mode, you might get slightly over
1MB/sec. So the ratio in performance could be about 20:1. Another
limitation may come about, if a backup software package is using
compression, in which case, depending on machine, performance could
drop to the 5MB/sec range (i.e. no longer limited by USB, but limited
by software performance).

Your ratio of 10:1 in performance cannot be immediately justified
by blaming the USB interface rate, but it is where I'd start looking.
Perhaps you can try some file transfer tests in the same environment
that Ghost uses, and see how long it takes to transfer a 1GB sized file ?

Paul

 

[Dave Neve]

Thanks Paul

I'm gonna give your reply to a friend who works in IT and he's gonna come
over and look at my setup.

Regards