CentOS - Aug 2015 - rsync stuck at +- 50 MB/s, cp and scp are +- 200 MB/s

Hi,

i have two servers, connected to to the lan by 10Gb with 10Gb and DAS
hardware raid.

Each system con read and write locally or to the 10G iscsi by more than
200 MB/s.

Now I have to transfer backups form A to B and doing this with rsync
always stuck at +- 48-50MB/s no matter which options, compressions,
encryption etc I use. Even the plain default rsync is at that 50 Mb limit.

coyp by scp goes up to 200 MB/s.

Copy from and to my workstation with scp from or to both servers is at
1Gb limit (so +- 100 MB/s)


Why is rsync stuck at +- 50 MB/s ? Any suggestions hints ...

	Thanks and regards . G?tz

-- 
G?tz Reinicke
IT-Koordinator

Tel. +49 7141 969 82420
E-Mail goetz.reinicke at filmakademie.de

Filmakademie Baden-W?rttemberg GmbH
Akademiehof 10
71638 Ludwigsburg
www.filmakademie.de

Eintragung Amtsgericht Stuttgart HRB 205016

Vorsitzender des Aufsichtsrats: J?rgen Walter MdL
Staatssekret?r im Ministerium f?r Wissenschaft,
Forschung und Kunst Baden-W?rttemberg

Gesch?ftsf?hrer: Prof. Thomas Schadt

Usually problem in encryption.

try cipher arcfour or apply hpn patches to ssh. (
http://www.psc.edu/index.php/hpn-ssh)

--
Eero

2015-08-11 12:37 GMT+03:00 G?tz Reinicke - IT Koordinator <
goetz.reinicke at filmakademie.de>:
> Hi,
>
> i have two servers, connected to to the lan by 10Gb with 10Gb and DAS
> hardware raid.
>
> Each system con read and write locally or to the 10G iscsi by more than
> 200 MB/s.
>
> Now I have to transfer backups form A to B and doing this with rsync
> always stuck at +- 48-50MB/s no matter which options, compressions,
> encryption etc I use. Even the plain default rsync is at that 50 Mb limit.
>
> coyp by scp goes up to 200 MB/s.
>
> Copy from and to my workstation with scp from or to both servers is at
> 1Gb limit (so +- 100 MB/s)
>
>
> Why is rsync stuck at +- 50 MB/s ? Any suggestions hints ...
>
>         Thanks and regards . G?tz
>
> --
> G?tz Reinicke
> IT-Koordinator
>
> Tel. +49 7141 969 82420
> E-Mail goetz.reinicke at filmakademie.de
>
> Filmakademie Baden-W?rttemberg GmbH
> Akademiehof 10
> 71638 Ludwigsburg
> www.filmakademie.de
>
> Eintragung Amtsgericht Stuttgart HRB 205016
>
> Vorsitzender des Aufsichtsrats: J?rgen Walter MdL
> Staatssekret?r im Ministerium f?r Wissenschaft,
> Forschung und Kunst Baden-W?rttemberg
>
> Gesch?ftsf?hrer: Prof. Thomas Schadt
>
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>

Hi,

I tried different encryptions like arc four, but always with the same result.
BTW: googling shows some similar questions and they are stuck on set same speed
+-.

But non of that solutions helped me.

	/G?tz



> Am 11.08.2015 um 12:14 schrieb Eero Volotinen <eero.volotinen at
iki.fi>:
> 
> Usually problem in encryption.
> 
> try cipher arcfour or apply hpn patches to ssh.
(http://www.psc.edu/index.php/hpn-ssh
<http://www.psc.edu/index.php/hpn-ssh>)
> 
> --
> Eero
> 
> 2015-08-11 12:37 GMT+03:00 G?tz Reinicke - IT Koordinator
<goetz.reinicke at filmakademie.de <mailto:goetz.reinicke at
filmakademie.de>>:
> Hi,
> 
> i have two servers, connected to to the lan by 10Gb with 10Gb and DAS
> hardware raid.
> 
> Each system con read and write locally or to the 10G iscsi by more than
> 200 MB/s.
> 
> Now I have to transfer backups form A to B and doing this with rsync
> always stuck at +- 48-50MB/s no matter which options, compressions,
> encryption etc I use. Even the plain default rsync is at that 50 Mb limit.
> 
> coyp by scp goes up to 200 MB/s.
> 
> Copy from and to my workstation with scp from or to both servers is at
> 1Gb limit (so +- 100 MB/s)
> 
> 
> Why is rsync stuck at +- 50 MB/s ? Any suggestions hints ...
> 
>         Thanks and regards . G?tz

El 11/08/2015 a las 06:37 a.m., G?tz Reinicke - IT Koordinator
escribi?:
> Hi,
>
> i have two servers, connected to to the lan by 10Gb with 10Gb and DAS
> hardware raid.
>
> Each system con read and write locally or to the 10G iscsi by more than
> 200 MB/s.
>
> Now I have to transfer backups form A to B and doing this with rsync
> always stuck at +- 48-50MB/s no matter which options, compressions,
> encryption etc I use. Even the plain default rsync is at that 50 Mb limit.
>
> coyp by scp goes up to 200 MB/s.
>
> Copy from and to my workstation with scp from or to both servers is at
> 1Gb limit (so +- 100 MB/s)
>
>
> Why is rsync stuck at +- 50 MB/s ? Any suggestions hints ...
rsync is not a like a copy, it checks from both sides that the file to 
copy is not the same on the other side. Copying something is straight 
forward, it dont wait to a remote check of the files metadata or 
attributes (last modification, permissions, etc). Access disk time could 
explain this...
I dont know how you are using rsync... if you are using the network 
protocol or a nfs mount.
check this also, if the rsync is using a single tcp connection for each 
file, and you have a lot of small files, the problem could be the slow 
start congestion algorithm of tcp (scp uses a single conection to copy, 
im sure of that. i dont know how rsync protocol works)
Also, if you have a lot of small files, it will take a lot of access 
time (disk seek time) for each to fetch this information and then start 
the copy.

See if you can do a iostat on each server doing a scp and a rsync to see 
the disk usage diference... if you find that you have a large queue on 
disk when using rsync, thats the problem...


I hope this helps to point the way to solve your problem.
Saludos, Juan.