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I've been looking around for an answer to my problem but I can't find anything. My problem is that I recently bought a new computer, Lenovo G500, it has 2xUSB3 and 1xUSB2, Intel pentium I3 2.4 GHz x4 and 6 Gib memory, it came with windows 8 but I removed it and installed Ubuntu 14.04.

The problem is, if, lets say, I try to copy one folder/file (doesn't matter the size) from/to my hard drive from/to the usb device, I have a WD 1tb usb 3 external HD but it does it with usb pens or another HD I have, it will copy fine, with high speeds. However, if I was to start a second copy/transfer while the first one is still going it will make the copying speed for both actions almost come to a stand still and take several hours.

This is not the only problem, the other problem is that while the copying is going on if I open any windows or programs they will take a very long time (may be up to 1 min) to open/start.

If I open the system monitoring it tells me that only 10% (+ or -) CPU usage, so memory is not an issue.

Any ideas what could be going on?

Thank you very much in advance

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What worked for me on a laptop was to change the disk scheduler. This can be cone in three ways:

Test it by typing at the command line (ctrl+alt+t)

echo cfq | sudo tee /sys/block/sda/queue/scheduler

and replace "sda" with the device name of your devices. Do this for both of your disks. You can check what scheduler is in use by entering

cat /sys/block/sda/queue/scheduler

reboot to revert to standard if this does not work.

To make the changes permanent, place the command into /etc/rc.local or add a kernal option elevator=cfq

more information

Since I wrote this answer, I have changed my strategy. I now user the cfq disk scheduler, but have added the 'noautogroup' flag to my boot parameters.

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Thank you, I will check it later (as I'm in a different computer right now) and get back to you with the outcome. – user300695 Jul 7 '14 at 6:25
Ok, I finally I had a small break from work and I managed to do this. Unfortunately it didn't work it tells me straight away:bash: /sys/block/sda/queue/scheduler: Permission denied, any suggestions what would that be? It doesn't even give me the chance to put my administrator password. – user300695 Jul 11 '14 at 9:32
Sorry - the command should be started with sudo--- sudo cat /sys/block/sda/queue/scheduler – Charles Green Jul 11 '14 at 13:14
Hi; the second command was fine, that one told me noop [deadline] cfq, is the first command you put in the orignial answer: sudo echo cfq > /sys/block/sda/queue/scheduler that tells me despite sudo: bash: /sys/block/sda/queue/scheduler: Permission denied – user300695 Jul 12 '14 at 14:35
Ah - I always have trouble with sudo and echo - what you can do instead is type sudo -i which will run sudo as a shell, then type echo cfq > /sys/block/sda/queue/scheduler within the shell to get the command to run. You will need to type exit to leave the shell, and exit again to close the terminal – Charles Green Jul 12 '14 at 14:46

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