On Sat, Sep 10, 2016 at 01:22:45AM -0400, Neal P. Murphy wrote: > On Fri, 9 Sep 2016 23:14:30 -0500 > David Wright <deb...@lionunicorn.co.uk> wrote: > > Good eye! I was going to say it's not possible to get 110Mb/s over 802.11g; > 40-50 is closer tothe best I get. And 193Mb/s over 100Mb/s ethernet is right > out; best I've ever managed is maybe 97Mb/s, and 92-95 is more typical. > 11,034,157Mb/s on W/L and 19,338,838Mb/s on wired is *much* more believable. > > Unless one has a very fast multicore CPU with hardware crypto assistance, > very fast RAM and the data to be transferred cached in RAM, one will probably > never saturate a fastE or gigE link where one end must decrypt the data from > disk/cache then encrypt the data to scp, and the other end must decrypt the > data from scp then encrypt the data to disk. Even simple compression slows > transfer down far too much.
SSDs can routinely read 400-600 MB/s. No need to have everything cached in RAM. In 2010, the first generation of i5 CPUs with hardware support for AES could encrypt at about 15 MB/s, more than filling a 100 Mb/s pipe. Here's a table of recent CPUs with AES support, running with OpenSSL/LibreSSL. https://calomel.org/aesni_ssl_performance.html It's in megabytes per second, so assume 1000/8 = 250 MB/s is the bandwidth of a gigabit ethernet NIC. Anything which can do 2x that can approach encrypting/decrypting from SSD, then decrypting/encrypting over an SSH connection. There are a lot of 500s and above on that chart. And that's per-core, so even the 250+ CPUs can fill a gig-e pipe while reading from SSD. Nor are they monstrously expensive: an AMD FX-6300 is $90, a motherboard for it could be another $90, and you can get a decent SSD for $100 these days. A $400 desktop can be put together that can saturate a gig-E link with encrypted traffic from an encrypted disk. Truly we live in marvelous times. -dsr-
