rsync over SSH (NSA320 to NAS326) limited to 4MB/s due to ssh cipher cpu usage?

AlexSA · October 2022

I'm trying to do a large rsync between two NAS, a 320 and a 326, noticed it's very slow.

I can see ssh using about 80% cpu on the source box (the 320) (rest is rsync).

I can't seem to find a faster cipher compatible with both boxes. Arcfour doesn't work. Can't disable encryption completely? Any tips please? This is going to take a long time otherwise.

I could do something radical like mount an NFS on one box but don't want to mess with NFS config, would rather stick to SSH if possible.

Thanks.

AlexSA · October 2022

Hmm. When i run the command in reverse (i.e. from the NAS326) and using -c arcfour, it doesn't error out, but it also doesn't seem to speed anything up! not sure which cipher is actually in use.

but CPU on the older 320 is still maxing out with SSH

Mijzelf · October 2022

Indeed the 320 cannot handle encryption very well. My 325 did around 1MB/sec, and a 320 has a weaker SoC. The option 'cypher=none' used to be in ssh, but is dropped years ago. Not only doesn't it hide your login, but it is also not possible to detect a man in the middle attack. The servers certificate is used in the encryption, and so the server can prove he has the certificate. Without encryption, no certificate.

Anyway, as the 320 doesn't support ssh, and AFAIK nor the 320 or the 326 support rsync over ssh, I suppose you are using 3th party software. In that case you can run rsync in daemon mode on one of the boxes.

rsync over SSH (NSA320 to NAS326) limited to 4MB/s due to ssh cipher cpu usage?

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