Speed issue with SSH/Unison on SuSE9.2

The place to post if you need help or advice

Moderators: ChrisThornett, LXF moderators

Speed issue with SSH/Unison on SuSE9.2

Postby photobod » Mon May 30, 2005 9:37 pm

I'm trying to set up Unison to sync backups on a small LAN. It all works fine, except that the transfer rate is very slow compared to the normal speed of the LAN.

The PC's are both using Unison on SuSE 9.2, connected by SSH. I'm getting about 80KB/sec on a 100Mb/sec LAN that normally manages about 10MB/sec over NFS.

Is the lack of speed due to ssh or to Unison? Is there any way to tweak whichever is causing the slowdown to improve matters?

Thanks,

Neil Lewis
photobod
 
Posts: 94
Joined: Thu Apr 21, 2005 7:18 pm
Location: London

RE: Speed issue with SSH/Unison on SuSE9.2

Postby Rhakios » Mon May 30, 2005 9:41 pm

ssh can slow things down, especially on older hardware due to the encryption overhead, but even so I can get 4MB/sec out of a 600MHz Celeron. So, I expect it's the Unison part of the set up.
Bye, Rhakios
User avatar
Rhakios
Moderator
 
Posts: 7634
Joined: Wed Apr 06, 2005 11:18 pm
Location: Midlands, UK

RE: Speed issue with SSH/Unison on SuSE9.2

Postby photobod » Mon May 30, 2005 9:45 pm

Thanks Rhakios. At least I can now concentrate on Unison as the cause of the problem.
photobod
 
Posts: 94
Joined: Thu Apr 21, 2005 7:18 pm
Location: London

RE: Speed issue with SSH/Unison on SuSE9.2

Postby nelz » Mon May 30, 2005 10:20 pm

I've just tried a Unison sync and got around 3MB/s. That was transferring a lot of small mail files, where you would expect overhead to be a problem. With a single large compressed file, I get around 1.3MB/s, so Unison is certainly capable of more than 80KB/s.

You can reduce the SSH overhead by switching to a less CPU-intensive cipher. I have set the default to blowfish, by adding "Cipher blowfish" to /etc/ssh/ssh_config on both machines.
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)
User avatar
nelz
Site admin
 
Posts: 8493
Joined: Mon Apr 04, 2005 11:52 am
Location: Warrington, UK

RE: Speed issue with SSH/Unison on SuSE9.2

Postby photobod » Wed Jun 01, 2005 9:58 pm

That's very useful info, thanks Nelz.
photobod
 
Posts: 94
Joined: Thu Apr 21, 2005 7:18 pm
Location: London


Return to Help!

Who is online

Users browsing this forum: No registered users and 4 guests