LiveCD copying over USB 2.0 speed ?

Forum: User Feedback
Topic: LiveCD copying over USB 2.0 speed ?
started by: setecio

Posted by setecio on Aug. 10 2008,09:33
I was using DSL 4.4.3 live CD last week to backup the data on a borked winXP machine before trying a repair install of XP.

It took about 1 hour to copy over 3GB of data onto a USB flash drive using Emelfm. Given that the USB flash drive was a fast Corsair 4GB and the USB port was 2.0, is this not very slow? Is there a setting I need to adjust in DSL to get a fast copying speed ? Is there a better package than Emelfm to use ? Or is this slow speed all that I could expect ?


Posted by curaga on Aug. 10 2008,10:19
Was it many small files or some big ones?
Usb flash drives are *very* slow with small files, way under 1/10 of their rated write speed.
This is caused by the flash mechanics of big erase blocks.

Your speed was about 0.9mb / s.

Then I recall there was an issue with usb 2.0 by default preventing someone's usb boot, so only 1.1 is loaded by default. You need to "sudo modprobe ehci_hcd" to get usb 2.0 speeds.

Posted by WDef on Aug. 10 2008,15:51
usb2.0 is disabled by default?

I can't help but think that's the wrong around to what it ought to be - that it should be enabled by default and disabled with a boot code.  Same with dma.

Was there only one person who had problems booting because usb2.0 was enabled?

Posted by roberts on Aug. 10 2008,16:10
It is not disabled. My main machine for DSL is usb 2.0 pendrive booted. When I have to use an older machine with only 1.1, I notice the difference.

One can always do an lsmod and system stats and see the module.

Posted by WDef on Aug. 10 2008,16:32
Thanks for clarifying that, I thought it sounded a bit odd.
Posted by curaga on Aug. 10 2008,17:23
? There are only usb-uhci and usb-ohci loaded in knoppix-autoconfig of DSL 4.4.3, no mention of ehci..

Edit: Ah. It's in minirt24.gz instead.

Posted by setecio on Aug. 10 2008,19:48
It was a mixture of file sizes but there was 1.3GB of photos which were at least 1MB each, a few hundred MB of music and the rest a mixture of other, word / excel etc. So the majority were large files. It still seems very slow to me.
Posted by jaapz on Aug. 10 2008,21:48
Well, it does matter what u call large, i, for instance, dont think 1mb is very large. So if u got many photo's of 1mb that could have been the problem.
Posted by stupid_idiot on Aug. 11 2008,01:50
Personal experience:
Imation 4GB USB2.0 pendrive which I bought this year. Transferring 1.5G of mp3s took about 20 minutes on my Debian 'Lenny' install w/ a very recent 2.6 kernel. 1 hour for 3G sounds reasonable (but very slow in actual terms).

Posted by setecio on Aug. 11 2008,07:49
OK thanks, it seems OK then if it is similar to speeds you experience. (Yes reasonable, but slow in actual terms )

(I called the 1MB large only in comparison to having lots of very small word or excel files.)

(I also took the drive out and connected it up as a slave over IDE and transfer speed was very fast - that's really why I'm asking. I know USB is a different interface but was just checking it was operating as one would expect.)

Posted by WDef on Aug. 17 2008,09:24
[ nb: You should save a lot of time copying to flash if you zip/tar/rar all your files together and copy them across as one big file. ]

These speeds do certainly sound way under the (what?) 20-40MB/s claimed write speeds for brand name flash sticks.  usb2.0 shouldn't be imposing any bottleneck (max 60MB/s), assuming there's no other bottleneck that is.

Someone here posted their fairly unscientific results for write speeds for different brand name flash drives using both dsl and Windows a while back, saying the write speeds came in way under spec and that the '20x' (@ 150kB/s) etc designations appeared to be almost meaningless.  

But then - you say the same drive got much faster transfer speeds when seen as an ide device.  So then it is not the device that is the problem, suggesting you are not actually getting usb2.0 speeds at all.

Do we have any hardware engineers out there who could comment?

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