Brian Stempin on 24 Mar 2008 09:58:38 -0700

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Re: [PLUG] Disk Transfer Speeds

Oh, one other thing:

Are you being careful between MBits and MBytes?  There's a pretty large difference.  A 100Mbit/sec connection = 12.5 MBytes/sec (remember:  there are 8 bits per byte).  Once you count in TCP/IP overhead (usually between 15% and 25%, depending on who you ask, jumbo frame settinsg, etc), 9MBytes/sec is a fair throughput.  I want to say that the fastest I've ever gotten on a 100Mbit connection was around 10.2MBytes/sec.

Anyways, all of that text to say, "Even if you had faster hard drives, your network throughput wouldn't go up that much anyway, if at all."

On Mon, Mar 24, 2008 at 12:42 PM, Brian Vagnoni <> wrote:
From what I've read network speed auto negotiation is a real throughput killer. Interfaces should be manually set to 100mB full duplex if the card and switch can handle it. Also check for accessive broadcast traffic another throughput killer.

Brian Vagnoni
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-----Original Message-----
From: Casey Bralla <>
Sent: Saturday, March 22, 2008 7:15 AM
To: Philadelphia Linux User's Group Discussion List <>
Subject: [PLUG] Disk Transfer Speeds

How fast are file transfers on your computer?

Recently, I noticed that some of my networked servers seemed very slow.  On large (100+
MByte) file transfers, I was getting rates less than 1 MBit/sec.  Changing out an old
10 MBit/sec hub to a 100 MBit/sec switch increased the speed to about 8-9 MBits/sec.
A little more investigation revealed that *local* transfers (on the same disk) maxed
out at about 9 MBits/sec.  This seems to point to a limitation on the disk itself.

This still seems slow to me.

I've got a fairly good computer:  AMD 3400+, 2 GBytes of RAM, Gentoo, KDE, ReiserFS,
Disk DMA active, with a half-dozen programs running.

I'm curious what speeds other people get with large files.  (Gotta be sure that the
file is bigger than the cache to keep from getting bogus numbers)


Casey Bralla
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