[Fwd: Re: [OpenAFS] Heavy performance loss on gigabit ethernet]

[Andrew Bacchi]

Forgot to send to the list.

Check that the switch and client is set to Full Duplex.  Even if you set
autoneg off on the server/client, the switch must match this setting.

ethtool eth0

Settings for eth0:
        .
	.
	.
        Advertised auto-negotiation: No
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
        .
	.
	.

On Wed, 2004-08-11 at 11:42, Enrico Scholz wrote:
> Hello,
> 
> we are using OpenAFS 1.2.11 in an environment where the fileserver has a
> 1000Mb/s ethernet interface and the clients 100Mb/s ones. With this
> setup we get really poor client-performance on large files; e.g. a 40 MB
> sized file needs nearly 4 minutes for the transfer.
> 
> | $ time cat kernel-source-2.4.22-1.2197.nptl.i386.rpm >/dev/null 
> | real    3m53.889s
> 
> 
> On another 1000Mb/s enabled machine or the fileserver itself, I get the
> full speed
> 
> | $ time cat kernel-source-2.4.22-1.2197.nptl.i386.rpm >/dev/null 
> | real    0m1.226s
> 
> 
> When enforcing 100Mb/s on the fileserver (ethtool -s eth0 speed 100
> autoneg off), the speed on the clients is ok:
> 
> | $ time cat kernel-source-2.4.22-1.2197.nptl.i386.rpm >/dev/null 
> | real    0m12.928s
> 
> 
> I can explain this with the dropping of AFS (UDP) packets in the
> involved network-components when the files are larger than the buffer
> in the switches. As these packages never reach the client, the server
> will have to resend them after a timeout.
> 
> Is this a general AFS problem and should I enforce the 100Mb/s by default? 
> Or, are there hidden switches in OpenAFS which enable something like TCP's
> sliding window algorithm? Or, does it work in other environments without
> problems and something is wrong with my network?
> 
> 
> 
> Some more details about the infrastructure: The fileserver is running
> with an e1000 NIC which is connected to a 3com 4900 Gigabit switch (L3
> enabled). On this switch, further 3com 43xx 100Mb/s switches are attached
> (upstream-ports are gigabit there also) on which the 100Mb/s clients are
> connected. Clients and server are running with a Fedora Core 1 kernel and
> OpenAFS 1.2.11.
> 
> 
> 
> 
> Enrico
> _______________________________________________
> OpenAFS-info mailing list
> OpenAFS-info@openafs.org
> https://lists.openafs.org/mailman/listinfo/openafs-info
> 
-- 
Facade: Provide a unified interface to a set of interfaces in a
subsystem.

Andrew Bacchi
Staff Systems Programmer
Rensselaer Polytechnic Institute
phone: 518 276-6415  fax: 518 276-2809

http://www.rpi.edu/~bacchi/
-- 
Facade: Provide a unified interface to a set of interfaces in a
subsystem.

Andrew Bacchi
Staff Systems Programmer
Rensselaer Polytechnic Institute
phone: 518 276-6415  fax: 518 276-2809

http://www.rpi.edu/~bacchi/