transfert rate

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mouche
Posts: 4
Joined: 25 Mar 2009, 15:23

transfert rate

Post by mouche » 01 Apr 2009, 14:23

After some struggle with sarge and etch, I finally installed lenny on my bubba 1. Everything is perfect except with ssh and rsync.

-first rsync is very slow: about 800kB/s, it took me about 3 days non-stop to make a complete backup. I usually use the following formula, via ssh or nfs with the same results:
rsync -avh --progress --delete --ignore-existing --delete-excluded --prune-empty-dirs --stats --rsh='ssh' /local/dir me@bubba:/remote/dir

- while making this long backup, i regulary ssh bubba and htop show me that "ssh me@notty" (or somthing like that) is eating 80 to 90% of the CPU load while rsync is eating the rest.

What I dont understand is why do I get these poor transfer rates between my computer and bubba while I can download an ISO with rtorrent at full speed (~2,5 MB/s) without any problem. And why does ssh eat up so much CPU?

Any answers or questions are very welcome?

bjorn
Posts: 88
Joined: 03 Jan 2007, 09:02

Post by bjorn » 02 Apr 2009, 14:27

Hi,

SSH uses encryption which is VERY expensive on the poor ARM9 cpu. You should not expect more than what you're seeing in terms of transfer-rate over ssh. A better alternative would probably be to mount the disk via NFS.

I get somewhere between 2.5 to 4 mb/sec (depending on if i use ext2 or ext3 on bubba) over NFS.

/Björn

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