ssh / scp slow on 10GBE

Stefan Priebe s.priebe at
Mon Jan 7 05:54:46 EST 2013

Hi Iain,

Am 04.01.2013 20:08, schrieb Iain Morgan:
>> openssl aes-128-cbc speed:
>> The 'numbers' are in 1000s of bytes per second processed.
>> type             16 bytes     64 bytes    256 bytes   1024 bytes   8192
>> bytes
>> aes-128-cbc     648664.33k   688924.90k   695855.45k   700784.64k 704027.06k
> As Tomas noted, the choice of MAC also impacts performance. The default
> is hmac-md5, but umac-64 at can provide significantly better
> performance.
Oh i didn't saw tomas mail - maybe he just replied to the list. I'm not 
subscribed. But i found his mail and will reply in a seperate email.

I tried now umac-64 at this gives me 400MB/s - is this the 
maximum i can expect through 10GBE? Link shows avg rate of 6,5Gbit/s.

> I'm assuming that the number you quoted in your original email was from
> an scp transfer. Be aware that it uses fairly coarse time granularity in
> its calculations, so transfers of small files can report deceptive
> values.
Yes it was from scp but just transfering one 20GB file. But i missed the 
disk speed problematic. In my original task i would just like to 
transfer as much data as possible (in memory - no disks involved).


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