Problems copy files to USB-Mass Storage device

if0720 · n00b Joined: 19 Mar 2003 Posts: 16

Hi,

i can plugin and mount my usb devices normaly. But then i copy a big file (~ 100MB) on that device, the copy command (also with drag & drop in konqueror) is finished very fast. I can even see the file on the device with the right size.
When i now plugoff the device and re-plugin - the file is not listed on the device anymore.

It seems to me, that the copy command says finished although it isn't. I compiled my kernel with some other USB options and with debug messages. No luck so far.
But then i copy a file to a usb-device i can see the IO-Transfers in the LOG although the copy command is finished.
During that transfers i can't unmount the device (because its busy i believe).

Is this a normal behaviour ? Does anybody else have this kind of problem.

Thanks in advance.

dentharg · Posted: Thu Feb 15, 2007 9:08 am Post subject:

Seems like you have some extreme caching for that device. The file is first copied to this cache and then quitely moved to the device in the background - at least that's what I think.
In KDE I always use "safely remove" for any usb stick I plug before removing it.

JeliJami · Veteran Joined: 17 Jan 2006 Posts: 1086 Location: Belgium

before you physically remove the device, run

if0720 · n00b Joined: 19 Mar 2003 Posts: 16

Thank you for your answers.
I added the 'sync' option in my /etc/fstab. This works great. The copy command takes as long as the file completly transfered.
Great hint davjel

What are the drawbacks you were talking about ?

JeliJami · Veteran Joined: 17 Jan 2006 Posts: 1086 Location: Belgium

With the sync option, not only all file operations are written directly to disc, but also all filesystem operations!

(see the comments of nephros, maguire and Gentree in
https://forums.gentoo.org/viewtopic-t-350769.html)

If you use the 'sync' option, you may also want to use the 'noatime' option (see man mount), and probably some others.
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if0720 · n00b Joined: 19 Mar 2003 Posts: 16

With the sync option in /etc/fstab set, file transfer to the usb-device is horrible slow - you cant use it

Just for testing i booted up with knoppix and found out, that in this distribution the transfer works with caching also. A 100MB file is "copied" in a second - but as mentioned - not realy copied.

OK obviously thats just the way coping to usb-device works in linux. I will use "safely remove" in kde now, although i would prefer to know when the file transfer is completed ...