[OpenAFS] Re: Speed of AFS

[Mitch Collinsworth]

On Wed, 2 Mar 2005, Lars Schimmer wrote:

> Joe Buehler schrieb:
> | Lars Schimmer wrote:
> |
> |> We get here round about 2-3 MB/Sec from server to client, and for some
> |> folks
> |> that's a bit to slow (on 100 MBit).
> |
> |
> | Try checking your network.  You might have a duplex misconfiguration
> | problem.  Or you might be dropping packets.  I've had my fair share
> | of this sort of thing to deal with -- fixing it helps AFS a lot.
>
> The network itself should be OK, full switched 100mbit network, every
> IP, every name only once, dhcp, ntp now on all PCs, so, from that point
> on, it seems to be OK.

The duplex mismatch issue is a huge speed killer, and none of the things
you mentioned are relevent to verifying it.  If you have managed switches
you need to make sure that either each switch port's duplex setting
matches that of the machine or switch plugged into it.  In other words
both ends of every cable must be configured the same.

auto <--> auto
full <--> full
half <--> half

Actually half <--> auto will work ok but the big thing many folks miss is
that full <--> auto will NOT work correctly.  If you do this the auto end
will configure itself to half and your throughput speed will be very
slow on that connection.

If you have unmanaged switches, every port is by default auto and you
must make sure everything connected to it is set to auto.

If you have any hubs, every port is by default half so you can set the
devices it connects to to either auto or half but not full.

Yes it's a bit confusing at first but it makes a huge difference.

-Mitch