topic Re: Linux rcp high throughput problem in Operating System - Linux

Linux rcp high throughput problem

Brem Belguebli — Tue, 30 Sep 2008 09:18:02 GMT

Hi,

I have a long distance (Europe --> Japan) 45 Mbs link over which I intend to transfer continuously 50 MB files through rcp (scp seems limited to 64k window size).

Linux rcp command doesn't seem to be as configurable as it's HP-UX pair by setting the SEND_BUF and RECV_BUF (rcp -S xxx -R xxx).

Is there any special linux rcp package that would allow that, or do I have to hack the default rcp code ?

The window size on the systems have already been increased.

Thanks

Re: Linux rcp high throughput problem

Ivan Ferreira — Tue, 30 Sep 2008 19:33:34 GMT

Try with something like:

dd if=filename bs= | rsh remotehost dd of=filename bs=

Check if you have better performance with different block sizes.

Re: Linux rcp high throughput problem

Brem Belguebli — Wed, 01 Oct 2008 16:29:51 GMT

Hi

Thanks Ivan, but it didn't make it, I've been playing with several block sizes and it never goes over 1.5 Mbs, which is logical, as the transfert protocol with your pipe is rsh (no setsockopt SO_SNDBUF in the netkit implementation)

I finally did it by using lftp, a bit tricky to parameter, but works fine when tuned.

Brem

Re: Linux rcp high throughput problem

Brem Belguebli — Wed, 01 Oct 2008 21:29:25 GMT

I'm having a little issue.

The ftp server (located in Japan is a HP-UX 11.23 wuftpd-2.6.1) runs with bufsiz 340k (ftpd -B 340).

I have 4 clients, located in Europe, on the same site, connected with Gb cards, 2 are Linux running lftp client with bufsiz 340k (set net:socket-buffer 340000) and 2 IA 64 HP-UX 11.23 running HP-UX ftp client with bufsiz 340000 (-B 340).
The 4 machines have tuned tcp parameters (window size > 500k).

the latency between the clients and the server is 250 ms.

The results obtained to transfer a 50 MB file from each machine are stable but embarrasing:

Linux: between 54 and 60 secs
HP-UX: between 2'10 and 2'40

What could explain such differences ?

Re: Linux rcp high throughput problem

Dennis Handly — Thu, 02 Oct 2008 06:35:43 GMT

>What could explain such differences?

Brem's HP-UX issue is in this thread:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1274515