Home » What is the fastest way to send massive amounts of data between two computers? [closed]

What is the fastest way to send massive amounts of data between two computers? [closed]

Solutons:


Since the servers are physically next to each other, and you mentioned in the comments you have physical access to them, the fastest way would be to take the hard-drive out of the first computer, place it into the second, and transfer the files over the SATA connection.

netcat is great for situations like this where security is not an issue:

# on destination machine, create listener on port 9999
nc -l 9999 > /path/to/outfile

# on source machine, send to destination:9999
nc destination_host_or_ip 9999 < /dev/sda
# or dd if=/dev/sda | nc destination_host_or_ip 9999

Note, if you are using dd from GNU coreutils, you can send SIGUSR1 to the process and it will emit progress to stderr. For BSD dd, use SIGINFO.

pv is even more helpful in reporting progress during the copy:

# on destination
nc -l 9999 | pv > /path/to/outfile

# on source
pv /dev/sda | nc destination_host_or_ip 9999
# or dd if=/dev/sda | pv | nc destination_host_or_ip 9999

  1. Do use fast compression.

    • Whatever your transfer medium – especially for network or usb – you’ll be working with data bursts for reads, caches, and writes, and these will not exactly be in sync.
    • Besides the disk firmware, disk caches, and kernel/ram caches, if you can also employ the systems’ CPUs in some way to concentrate the amount of data exchanged per burst then you should do so.
    • Any compression algorithm at all will automatically handle sparse runs of input as fast as possible, but there are very few that will handle the rest at network throughputs.
    • lz4 is your best option here:

      LZ4 is a very fast lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.

  2. Preferably do not unnecessarily seek.

    • This can be difficult to gauge.
    • If there is a lot of free space on the device from which you copy, and the device has not been recently zeroed, but all of the source file-system(s) should be copied, then it is probably worth your while to first do something like:

      </dev/zero tee >empty empty1 empty2; sync; rm empty*
      
    • But that depends on what level you should be reading the source. It is usually desirable to read the device from start to finish from its /dev/some_disk device file, because reading at the file-system level will generally involve seeking back-and-forth and around the disk non-sequentially. And so your read command should be something like:

      </dev/source_device lz4 | ...
      
    • However, if your source file-system should not be transferred entire, then reading at the file-system level is fairly unavoidable, and so you should ball up your input contents into a stream. pax is generally the best and most simple solution in that case, but you might also consider mksquashfs as well.

      pax -r /source/tree[12] | lz4 | ...
      mksquashfs /source/tree[12] /dev/fd/1 -comp lz4 | ...
      
  3. Do not encrypt with ssh.

    • Adding encryption overhead to a trusted medium is unnecessary, and can be severely detrimental to the speed of sustained transfers in that the data read needs reading twice.
    • The PRNG needs the read data, or at least some of it, to sustain randomness.
    • And of course you need to transfer the data as well.
    • You also need to transfer the encryption overhead itself – which means more work for less data transferred per burst.
    • And so rather you should use netcat (or, as I prefer, the nmap project’s more capable ncat) for a simple network copy, as has elsewhere been suggested:

      ###  on tgt machine...
      nc -l 9999 > out.lz4
      ###  then on src machine...
      ... lz4 | nc tgt.local 9999
      

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