How long should it take to download 1GB files over USB 2.0 ?

[JimL]

I have a Lexar multi card reader which uses USB 2.0 to transfer data to the computer. Yesterday it took a little over 6 min to transfer 1.15 GB to the hard drive. Cable, card and reader are all rated as USB 2.0. Is this normal or am I just using the wrong reader for my 2GB SanDisk Extreme III cards.
JimL

[jimk]

Sounds about right to me. USB1 would take at least 20 minutes

[neilp]

I'd say 6 minutes is really very fast for 1.15GB... most benchmarks are around the 7 minutes mark for 1GB. The main limitation here is the card speed, teh Extreme IIIs are quick, but only a few percent quicker than the Ultra IIs.

If you had USB1 then this would be something like 40+ minutes!

Neil.

[JimL]

Thanks. It sure seemed slow to me. So the limitation is the card read speed? I was thinking that I should be getting speeds similiar to one of the USB HDD (say a 100GB Maxtor or Western Digital portable)
JimL

[neilp]

Nope, as I said, the limitation is the card itself, not the card reader. A solid state flash memory is simply not as fast as a high speed hard disk running at 7200rpm...

Neil.

[Cadwell]

Oh dear... I'm going to disagree with everyone again. My Sandisk Extreme III 2GB CF cards take just over 3 minutes each to transfer to the PC for a full card. This is using a USB 2.0 Hi-Speed card reader and interface on the PC. That is about 50% of the Extreme IIIs quoted sequential read speed of 20MB/s. Of course, you never get the quoted maximum but I'm probably getting around 10MB/s.

[neilp]

One thing to note is that the transfer speed depends heavily on the number and size of the files. If Jim's card has many smaller files, e.g. lots of JPGs, then it will be slower than say a card which is full of larger files e.g. 12 megapixel RAW images from a 1D something... Glenn - is your 3 minutes the same for both JPG and RAW?

Neil.

[Cadwell]

I can't remember the last time I shot JPEG, Neil, so I wouldn't want to hazzard a guess as to the time for a card full of them.

One other thing to note is that there are two types of USB 2.0 devices... "Full Speed" and "Hi-Speed". There's a significant difference in data rate between the two; 12Mb/s and 480Mb/s.

[brianpowers27]

There is something wrong if it takes that long. I routinely use my 6gb microdrive and can download 1-2 gig in 3-5 minutes or less.

I will note that some devices act goofy in windows and will not harness the full bandwidth but a reboot can restore functionality. IN windows you might see some level of dialog notifying you that the devices is not using its full potential.

or

Every device in the chain needs to be USB 2.0 compliant.
Camera.
USB hub if used.
Cabling
COmputer adapters.