[OpenAFS] UDP slowness remedies?

Eric Chris Garrison ecgarris@iupui.edu
Fri, 22 Oct 2010 13:44:14 -0400

On 10/22/10 1:29 PM, Dan Pritts wrote:
> I'm guessing you are going between Bloomington and Indianapolis so
> latency shouldn't be too high, but even 10ms surely will add up if the
> conversation goes back and forth a million times.

That's correct.

> I'm pretty sure you can run multiple vos move's in parallel, which would
> help dramatically.

We have some half-TB volumes though, those are still going to take days
at this rate.

> as far as your iperf results, my experience is that tuning UDP buffers
> generally is not necessary; the defaults are usually sufficient to get
> hundreds of megabits.

Is there a way to make vos moves do this?  I'm using the mvto script,
modified to use -localauth since the moves far exceed ticket lifetime.
I could modify it further if vos has any options for these big volumes.

> in UDP mode, iperf does not attempt to scale the bandwidth; it tries to
> send at whatever bandwidth you specify on the acommand line.   the
> default is 1Mbit/sec...is it possible that's where your 1mbit result
> came from?

Yes, I used the default for the initial 1Mbit/sec result.  In my email
to this list, I reported incorrectly that I changed the buffer size for
the second test; it was actually bandwidth. I used the -b 1024M option
on iperf for the second try like I mentioned, and it was nearly line
rate.  Which is why I asked here what I could do to speed up these AFS
transfers, since faster should be possible.