[GRLUG] External drive transfer rates

Bob Kline bob.kline at gmail.com
Sat Oct 20 15:20:23 EDT 2007

I run two versions of Linux.  Kubuntu
7.04,  and a recent version of Mandriva.

I recently acquired an external hard drive
housing, which takes IDE drives,  and has
a USB 2 interface.

When I use it I mount it using the command

mount -t ext3  /dev/X  /disk2

and then proceed to transfer files.

Transfer them slowly that is.  21GB in about
6 hours,  which works out to a little less than
8Mbps.  This does involve moving tens of
thousands of small files,  which does slow
things down some, but not this much.

Going through the same motions under
Mandriva yields a transfer rate about 3X
higher,  or about 24Mbps.  I take it the
default setting are different in some slightly
significant way.

Given the nominal USB 2 rate of 480Mbps,
this is not very impressive.  One does not
of course expect anything close to the
480Mbps,  but 80Mbps or so would seem to
be closer to reasonable expectations.  With
big files one even gets 70Mbps over a 100Mbps
Ethernet link.

Looking around online,  it's clear this is a
widespread problem.  The only solid lead I've
seen is to somehow suppress the "sync"
function,  which does seem to be standard.
It's clear how to do this using /etc/fstab,  but
as shown above,  I don't use that for now.

Does anyone have any tips or suggestions?
While the transfers are robust,  and in a
sense everything is working,  the rates are
almost too slow to be of interest.

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