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Re: transfer speed data

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Hi Mick,

On Wed, Dec 23, 2020 at 12:55:58AM +0000, mick crane wrote:
> I have a buster PC and a bullseye PC which are both supposed to have
> gigabyte network cards connected via a little Gigabyte switch box.

"gigabyte" is not a network speed. You probably mean gigabit; that
is 10⁹ bits per second, i.e. 1000 * 1000 * 1000 bits per
second.

GNU units can be useful to indicate what you can expect:

$ units gigabit
        Definition: 1e9 bit = 1e+09 bit
$ units megabyte
        Definition: 1e6 byte = 8000000 bit
$ units 1gigabit/sec megabyte/sec
        * 125
        / 0.008

So on a gigabit network the absolute maximum you could expect is
125MByte/sec. Note that's SI prefix mega- meaning million bytes, not IEC
binary prefix MiB, meaning 1024 * 1024 bytes.

> Transferring files between them, I forget which shows the transfer speed per
> file, either scp or rsync the maximum is 50 Mbs per file.

I shall assume that "50Mbs" means "50 megabytes per second" and not
what it literally means which is "50 Megabits per second", a
quantity one eighth as much.

scp and rsync add a lot of overhead, especially when operating on
relatively small files. On a gigabit network I find myself lucky to
get more than about 90MB/sec through ssh or rsync-over-ssh.

So I find 50MB/s plausible.

> Would you expect that to be quicker ?

Not really.

To get a more realistic idea of your network's performance use
something like Iperf. You still won't see the full 125MB/s but I'd
expect it to go over 100.

If you are trying to transfer files as fast as possible and don't
need encryption, consider netcat. If you do need the encryption of
ssh, but don't need the features of rsync, then "tar | ssh" will be
a little faster.

On a low latency network (like your local network) at gigabit+
speeds, compression won't make things faster.

Cheers,
Andy

-- 
https://bitfolk.com/ -- No-nonsense VPS hosting

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transfer speed data mick crane <mick.crane@gmail.com> - 2020-12-23 02:00 +0100
  Re: transfer speed data Bob Weber <bobrweber@gmail.com> - 2020-12-23 02:40 +0100
  Re: transfer speed data Georgi Naplatanov <gosho@oles.biz> - 2020-12-23 02:50 +0100
  Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 02:50 +0100
    Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 03:00 +0100
      Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 16:10 +0100
        Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 16:40 +0100
          Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 17:00 +0100
            Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 17:20 +0100
              Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 18:40 +0100
  Re: transfer speed data Andy Smith <andy@strugglers.net> - 2020-12-23 05:00 +0100
    Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 11:00 +0100
      Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-23 15:50 +0100
        Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 17:10 +0100
        Re: transfer speed data David Wright <deblis@lionunicorn.co.uk> - 2020-12-23 18:50 +0100
          Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-23 19:20 +0100
            Re: transfer speed data David Wright <deblis@lionunicorn.co.uk> - 2020-12-24 02:30 +0100
              Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-24 10:10 +0100
                Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-24 17:10 +0100
      Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 16:20 +0100
        Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 17:20 +0100
          Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-24 17:10 +0100
    Re: transfer speed data deloptes <deloptes@gmail.com> - 2020-12-23 12:20 +0100
  Re: transfer speed data George Shuklin <george.shuklin@gmail.com> - 2020-12-23 23:00 +0100

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