so first, i think your problem doesn't have much to do with the rate at which the machines can send packets and has everything to do with the chatty back-and-forth nature of the protocol. I don't really know the protocol myself, actually, but this seems very likely; i've certainly run into it with other protocols/applications, e.g. TSM backups and windows file sharing.

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.

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

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.

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?


Eric Chris Garrison wrote:
So, I'm doing a mass migration of AFS volumes from one campus to
another.  Both machines have Gigabit interfaces, and we have a 20 Gig
link between the campuses that I understand to be not at all saturated.

However, I'm seeing a transfer rate of only about 30 Mbits/sec
(according to iftop) between the two machines.  I'm working on it with
my local network people, but it seems to be a UDP issue... if I use
iperf with defaults for UDP, I get about 1 Mbit/sec.  If I increase the
buffer size to 1024M, it screams along at 900+ Mbit/sec.

So how's this work with AFS/rx?  Is there something I can tweak to
increase UDP transfer speed?

Any advice would be appreciated.

Thanks,

Chris
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