[Discuss] Why are all my hard drives slow on Ubuntu? (new computer)

[Daniel Barrett]

So, I finally bought the Linux desktop of my dreams: fast CPU, 32GB RAM,
SSD RAID, running Ubuntu.

I get it home, turn it on, and ALL hard drives are slow, writing at about 1
MB/second. This includes both internal and external drives: the internal
SSD RAID (3ware 9750-4i card), an internal Western Digital Red (not on the
RAID card), and external drives using USB 3.0, Firewire, and eSATA. This is
on Ubuntu 12.04 LTS (kernel 3.5). I also tested using Ubuntu Live CDs for
13.04 (kernel 3.8) and prerelease 13.10 (kernel 3.11), and the problem
remained.

HOWEVER... when I boot on a Knoppix 7.2 live CD (kernel 3.9), the problem
completely goes away and all drives are fast.

Here's a 20MB file being copied from the SSD to itself on Ubuntu, which
takes 15 seconds:

    $ time cp bigfile bigfile2
    real    0m15.030s
    user    0m0.052s
    sys     0m0.000s

Now here is Knoppix:

    $ time cp bigfile bigfile2
    real    0m0.034s
    user    0m0.000s
    sys     0m0.013s

Likewise, when I boot into Windows 7 (it's a dual boot machine), the
drives are perfectly fast.

>From these tests, I assume that the default Ubuntu configuration is the
culprit.  Does anybody know the magical incantation that will make the
drives run at full speed and stay that way after reboots?
(e.g., echo 'no' > /sys/kernel/be-godawful-slow)

My motherboard is an ASUS P9X79 if that makes a difference.

Thank you very much for any insights!
Dan

--
Dan Barrett
dbarrett at blazemonger.com