rsync takes long pauses in xfer ?

[ericbambach1 at discover.com]

Marc,

        Well you can remove the timestamp checks by adding  "--size-only". 
If that speeds things up or removes the long "pauses" the timestamps were 
to blame. If the behavior is the same then I'm wrong. If I'm right then 
you might want to synchronize your clocks or use the " --modify-window" 
argument to rsync.

Eric Bambach | Discover
Senior Assoc. Programmer, Warehouse Infrastructure and Tools
2500 Lake Cook Road, Riverwoods IL 60015
P: 224.405.2896 ericbambach1 at discover.com




From:   Marc Rechté <marc3 at rechte.fr>
To:     <rsync at lists.samba.org>
Date:   06/12/2012 09:12 AM
Subject:        Re: rsync takes long pauses in xfer ?
Sent by:        <rsync-bounces at lists.samba.org>



Eric,

How would you know (debug) that size+time compare fails in a rsync session 
?

Thanks
Marc

Le 12/06/2012 15:39, ericbambach1 at discover.com a écrit :
> Alan,
>
>          What is the rsync command used? If it hits a large group of 
files
> with no differences (easy to believe across 12TB) but has to compare the
> checksums anyways (forced by you or failing the size+time compare) 
you'll
> be I/O bound with almost no corresponding network traffic as it just has
> to send the checksums.
>
>
> Eric Bambach | Discover
> Senior Assoc. Programmer, Warehouse Infrastructure and Tools
> 2500 Lake Cook Road, Riverwoods IL 60015
> P: 224.405.2896 ericbambach1 at discover.com
>
>
>
>
> From:   Alan McKay<alan.mckay+rsync at gmail.com>
> To:<rsync at lists.samba.org>
> Date:   06/12/2012 08:30 AM
> Subject:        rsync takes long pauses in xfer ?
> Sent by:<rsync-bounces at lists.samba.org>
>
>
>
> Hey folks,
>
> I did some googling on this but did not come up with much.  I'm using
> rsnapshot which uses rsync, and I notice some pretty long pauses in
> the xfers as you can see on this graph from "munin".   THe machine in
> question right at the moment is doing nothing but rsyncing (
> rsnapshoting ) some 12T of NAS storage to local disk, so there is
> nothing else going on at all.
>
> 
https://plus.google.com/u/0/photos/113518077816006248932/albums/5732421463318682369/5753139625064539250

>
>
> You can see a couple of spots in the graph where it just drops to
> nothing ( checking more closely you do see a very small bit of
> activity )
>
> Here is another graph from MRTG which records the traffic from the
> switch port side.  You can see around 2am it drops off pretty low,
> then from about 4am til about 7am it drops even lower.
>
> 
https://plus.google.com/u/0/photos/113518077816006248932/albums/5732421463318682369/5753140504922328322

>
>
> Is that normal?  Or is this something I should ask on the rsnapshot
> list (if there is one)?
>
> I did find something in google about depending on the types of files
> it can change xfer rate but not much detail.
>
> thanks,
> -Alan

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