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

[dbarrett at blazemonger.com (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.