[Beowulf] 10G and rsync

[Michael Di Domenico]

On Thu, Jan 2, 2020 at 10:35 AM Chris Dagdigian <dag at sonsorol.org> wrote:
>
> - I noticed you did not test small file / metadata operations. My past
> experience has found that this was the #1 cause of slowness in rsync and
> other file transfers. iperf and IOR tests are all well and good but you
> should run something like MDTEST to hammer the system on metadata and
> small file handling. If you are moving lots of tiny files or hundreds of
> thousands of directories etc this could be your problem
> - Single stream over 10gig has never been great for me doing big data
> movement. I get way more throughput by using rsync in parallel to
> migrate multi-stream either from a single 10gig connected host or a
> cluster of them

thanks.  this is definitely not a metadata issue, i'm only moving
100-200 files in total.  this is strictly a single stream transfer
problem with rsync

if i parallel the rsync, i can in fact increase the performance, but
the process that's doing the transfer (part of a bigger system) can't
handle that.

it just seemed unfathomable to me that rsync can't transfer at wire
past 1G speeds..