[Nottingham] Diagnosing a slow network

Martin martin at ml1.co.uk
Sun Nov 25 19:48:03 UTC 2012

On 25/11/12 14:52, Jason Irwin wrote:
> On 25/11/12 14:38, Nick Leverton wrote:
>> (doubly so I would imagine if you also ask rsync to do compression with
>> the -z flag which IME is rarely worth it across a fast local network).
> Yup, I had set -z out of habit, removed that and am now showing 25MB/s
>> One time, I started up rsync server daemon on one of the hosts and let
>> rsync on the other talk to it directly.
> Aye, I haven't started the daemon on the server; just didn't expect SSH
> to slow things down that much.
> Thanks for the explanation.

For diagnosing:

"top" and "iotop" are good first-look diagnostics to show bottlenecks.

"atop" is excellent and even better if you can unscramble the multitudes
of numbers!

For the rsync-ing:

Fastest should be to run an rsync server daemon.

Next best on a wired physically secure LAN is to use nfs and rsync
across a mount point.

(Don't try nfs over WiFi or further afield for obvious insecurity...)

>> I am a bit hung over today for some reason so can't remember more but
>> perhaps this may give you an avenue to explore.
> I'm not so bad meself.  A tad thirsty though.

I'm remarkably fine. That must have been some fine pure stuff that was
uncorked last night.

There was lots to drink from the heavens on the way back... :-( So no
probs there...

All good fun!


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