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Roger N. Clark (change us
Guest
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 Posted:
Tue Nov 01, 2005 5:40 am Post subject:
USB 2 card reader speeds? |
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Hi, Can someone give some specs on USB 2 compact flash,
card reader speeds? I bought a Lexar USB 2.0 card reader
and tested the transfer of raw files from a Lexar 80X 4GB
card. I got 3.7 megabytes per second reading to a Sony
S460P laptop, or about 12 minutes to read a nearly full
card. Is this reasonable, or are there
faster readers out there? If so, what models?
Thanks for any info.
Roger
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Rick Yerger
Guest
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| Posted:
Tue Nov 01, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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"Roger N. Clark (change username to rnclark)" <username@qwest.net> wrote in message news:4366EDAB.2090600@qwest.net...
| Quote: | Hi, Can someone give some specs on USB 2 compact flash,
card reader speeds? I bought a Lexar USB 2.0 card reader
and tested the transfer of raw files from a Lexar 80X 4GB
card. I got 3.7 megabytes per second reading to a Sony
S460P laptop, or about 12 minutes to read a nearly full
card. Is this reasonable, or are there
faster readers out there? If so, what models?
Thanks for any info.
Roger
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We use a Sandisk USB2.0 reader, and get just over 10MB/s
from Sandisk 1GB/2GB Ultra II CF cards to our PC. |
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teflon
Guest
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| Posted:
Tue Nov 01, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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I have a Lexar firewire reader than can read a full 1gb x80 CF in less than
three and a half minutes to a mac. Not sure if that helps you though. |
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ASAAR
Guest
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| Posted:
Wed Nov 02, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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On Tue, 01 Nov 2005 04:04:07 -0600, Ron Hunter wrote:
| Quote: | Card readers are limited by the speed of the card, the speed of the
interface, and the speed of the computer. They also have internal
overhead. All these things limit your throughput to much less than the
theoretical 480mbps of the USB 2.0 interface. 3.7 megabytes/second is
pretty reasonable for this combination and 2.6 gigabytes of data.
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No, that's not a reasonable top speed for USB 2.0 High Speed. You
should be able to do better than 3.7MB/sec with an 80x card, but
here you're closer to the theoretical limit. USB 2's 480mbps is
60MB/sec, and overhead will reduce that somewhat, but even if it's
reduced to 40MB/sec, that's still more than 10 times faster than
3.7MB/sec. An 80x card has a limit of about 12MB/sec (80 x
160kb/sec) which is about 3 times faster than the achieved
throughput. I'd guess that the main bottleneck would be writing to
the laptop's disk drive. If a fast drive on a desktop computer or
workstation was used instead, I wouldn't be surprised if the
transfer speed increased by as much as 100%. That would bring you
much closer to the rated speed of the card. To see what the best
possible throughput you could get is, it would be best to copy to a
RAM drive. Whenever copying to a real hard drive throughput will
always be reduced somewhat. Laptops generally use slower drives,
and have all sorts of power saving features that can reduce
performance, especially if the laptop has been operating long enough
to heat up a bit. Another thing to consider - a disk drive in need
of defragging can slow the transfer rate slightly or considerably,
depending on how bad the fragmentation is. |
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Roger N. Clark (change us
Guest
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| Posted:
Wed Nov 02, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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Bill Hilton wrote:
| Quote: | Roger wrote ...
I bought a Lexar USB 2.0 card reader
and tested the transfer of raw files from a Lexar 80X 4GB
card. I got 3.7 megabytes per second reading to a Sony
S460P laptop, or about 12 minutes to read a nearly full
card.
I know you have a Ph.D. from M.I.T. but are you sure these numbers add
up? (g) 12 minutes @ 3.7 MB/sec implies about 2.7 GB, not the almost 4
GB your card will hold. Or doing the math a different way, 4 GB @ 3.7
MB/sec would be about 18 minutes.
If my math is right then your card reader is maybe 20% slower than the
reader I'm using, which takes about 7 minutes for a full 2 GB card.
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Well Bill, I really messed that one up. I looks like
I should have used my reading glasses (seriously).
Those trick or treaters kept interrupting me (a couple
hundred of them last night).
The real numbers I got were: 3,144,746,081 bytes transferred
in 468 seconds = 6.7 megabytes per second, or about
10 minutes per 4 GByte card. This is much better.
Roger |
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Ed
Guest
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| Posted:
Wed Nov 02, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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I just filled up my Patriot 2 GB card (133x). It transferred 1.88 GB in
exactly 2 minutes using a Sandisk 12-in-1 card reader. I think this means
15.7 MB/second.
Computer is a Dell 4550, 3.06 GHz, 640 MB RAM.
I guess my cheapy card (only $125) is doing pretty darn fast transfers.
Ed
"Roger N. Clark (change username to rnclark)" <username@qwest.net> wrote in
message news:4366EDAB.2090600@qwest.net...
| Quote: | Hi, Can someone give some specs on USB 2 compact flash,
card reader speeds? I bought a Lexar USB 2.0 card reader
and tested the transfer of raw files from a Lexar 80X 4GB
card. I got 3.7 megabytes per second reading to a Sony
S460P laptop, or about 12 minutes to read a nearly full
card. Is this reasonable, or are there
faster readers out there? If so, what models?
Thanks for any info.
Roger |
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Bob Williams
Guest
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| Posted:
Thu Nov 03, 2005 5:40 am Post subject:
Re: USB 2 card reader speeds? |
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Ron Hunter wrote:
| Quote: | Bob Williams wrote:
Roger N. Clark (change username to rnclark) wrote:
Hi, Can someone give some specs on USB 2 compact flash,
card reader speeds? I bought a Lexar USB 2.0 card reader
and tested the transfer of raw files from a Lexar 80X 4GB
card. I got 3.7 megabytes per second reading to a Sony
S460P laptop, or about 12 minutes to read a nearly full
card. Is this reasonable, or are there
faster readers out there? If so, what models?
Thanks for any info.
Roger
The USB 2 (High Speed) Interface specification is 480 Mbits/sec.
Assuming 8 bits/byte that would indicate a top speed of 60 MB/sec.
If your reader advertises that it is USB 2 High Speed compliant, it
should be able to download data at 60 MB/sec.
Your observed download speed is more a function of the card speed than
the reader speed.
What Operating System, CPU speed are you using, and how much RAM do
you have installed?
Bob Williams
Of course most computers aren't capable of TAKING the data at 60MB/sec,
even if any USB 2.0 device could provide it that fast.
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Absolutely Right.
Especially with a laptop
Bob |
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Rick Yerger
Guest
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| Posted:
Thu Nov 03, 2005 5:41 am Post subject:
Re: USB 2 card reader speeds? |
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"ASAAR" <caught@22.com> wrote in message news:lmrhm15q1l0mt7j6a3imju6f68gkjgkmpt@4ax.com...
| Quote: | On 02 Nov 2005 09:53:59 -0600, David Dyer-Bennet wrote:
It is also not generally known that if you have a USB hub with a USB
1.1 device plugged in, it will NOT transfer data from any device on
that hub faster than the 1.1 speed (12mbps).
The booklet with my current Belkin 2.0 hub explicitly claims
otherwise.
Which explains why "It is also not generally known. . ." :)
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LOL
| Quote: | However, I recall that IDE channels (at least as originally
implemented) slowed down to the slowest mode used by either device.
That meant that with 2 IDE channels (handling up to 4 drives), the
hard drive would be the "Master" on one channel, and the slower CD
drive (single or double speed back then) should be attached to the
other cable that was plugged into the other IDE channel.
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True, and it is also true for mixed single-ended/LVD devices
on older SCSI controllers. One single-ended device on a
channel will drop the entire buss down to single-ended.
| Quote: |
I think that some of the early ethernet hubs worked as Ron
described, where all 100mbps devices would slow down to 10mbps speed
if a slow device was plugged in. I don't know if that was also true
or not for early USB 2.0 hubs if a USB 1.x device was attached.
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