Slow disk write speeds over network

Matt Levine matt at
Mon Jun 9 15:51:55 PDT 2003

On 6/9/03 6:16 PM, "Eric Anderson" <anderson at> wrote:

> Chuck Swiger wrote:
>> Eric Anderson wrote:
>>> Ok, I have a file server (NFS) running FreeBSD 4.8-RC1, which is
>>> having incredibly slow disk write speeds.  Locally, doing something like:
>>> dd if=/dev/zero of=/partition/testfile
>>> Shows 14MB/s - which is what I expect..
>>> However, ftping a file or cp'ing over NFS shows speeds less than 1MB/s
>>> - which is not what I would expect - it's got gigabit ethernet, and
>>> has very fast read times (via ftp or nfs) over the network.
>> If the slowdown was only with regard to NFS, I'd ask you about what your
>> NFS clients looked like.  However, if you're seeing a slowdown for FTP
>> and other network protocols, it's more likely to be a physical problem
>> with cabling, a NIC getting flaky, or something along those lines.
> I see it in both NFS and ftp transfers, but like I said in one of my
> other notes, I have 4 network cards in this machine, all act the same way.
>> Do you have this connected to a managed switch so that you can take a
>> look at the interface statistics for problems?  Maybe try cranking the
>> NIC down from gigabit to 100Mbs ethernet speed and see whether that
>> makes a difference?
> Yes - and I just tried that suggestion - same thing.  No help.
> Interfaces look ok.

Not to beat a dead horse, but are these the same nics as in the other
machines?  Is the switch manageable?  Does it agree with the nic(s) on
speed/duplex?  Tried turning off autonegotiate and forcing on both sides?

This has all the symptoms of a duplex mismatch.

> Eric

Matt Levine <matt at>

"The Trouble with doing anything right the first time is that nobody
appreciates how difficult it was."  -BIX

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