mscp/README.md

mscp

mscp, a variant of scp, copies files over multiple ssh (sftp) sessions. Multiple threads in mscp transfer (1) multiple files simultaneously and (2) a large file in parallel. It may shorten the waiting time for transferring a lot of/large files over networks.

You can use mscp like scp, e.g., mscp example.com:srcfile /tmp/dstfile. Remote hosts only need to run sshd supporting the SFTP subsystem, and you need to be able to ssh to the hosts (as usual).

Differences from scp are:

• remote glob on remote shell expansion is not supported.
• remote to remote copy is not supported.
• -r option is not needed.
• and any other differences I have not noticed and implemented...

Build

mscp depends on libssh.

• macOS

brew install libssh

• ubuntu

sudo apt-get install libssh-dev

• rhel

sudo yum install libssh-devel

Clone and build this repositoy.

git clone https://github.com/upa/mscp.git
cd mscp

mkdir build && cd build
cmake .. && make

# install the mscp binary to CMAKE_INSTALL_PREFIX/bin (usually /usr/local/bin)
make install

Run

• Usage

$ mscp
mscp v0.0.0: copy files over multiple ssh connections

Usage: mscp [vqDCHdh] [-n nr_conns]
            [-s min_chunk_sz] [-S max_chunk_sz]
            [-b sftp_buf_sz] [-B io_buf_sz]
            [-l login_name] [-p port] [-i identity_file]
            [-c cipher_spec] source ... target

    -n NR_CONNECTIONS  number of connections (default: half of # of cpu cores)
    -s MIN_CHUNK_SIZE  min chunk size (default: 64MB)
    -S MAX_CHUNK_SIZE  max chunk size (default: filesize / nr_conn)
    -b SFTP_BUF_SIZE   buf size for sftp_read/write (default 131072B)
    -B IO_BUF_SIZE     buf size for read/write (default 131072B)
                       Note that this value is derived from
                       qemu/block/ssh.c. need investigation...
    -v                 increment verbose output level
    -q                 disable output
    -D                 dry run

    -l LOGIN_NAME      login name
    -p PORT            port number
    -i IDENTITY        identity file for publickey authentication
    -c CIPHER          cipher spec, see `ssh -Q cipher`
    -C                 enable compression on libssh
    -H                 disable hostkey check
    -d                 increment ssh debug output level
    -h                 print this help

• Example: copy an 8GB file on tmpfs over a 100Gbps link
  • Two Intel Xeon Gold 6130 machines directly connected with Intel E810 100Gbps NICs.

$ mscp /tmp/test.img 10.0.0.1:/tmp/
[===============================================================] 100% 8GB/8GB 3.02GB/s 

• -v options increment verbose output level.

$ mscp test 10.0.0.1:
[===============================================================] 100% 13B/13B 2.41KB/s 

$ mscp -v test 10.0.0.1:
file test/test.txt (local) -> ./test/test.txt (remote) 9B
file test/test2/2.txt (local) -> ./test/test2/2.txt (remote) 2B
file test/1.txt (local) -> ./test/1.txt (remote) 2B
copy start: test/test.txt
copy start: test/1.txt
copy start: test/test2/2.txt
copy done: test/1.txt
copy done: test/test2/2.txt
copy done: test/test.txt
[===============================================================] 100% 13B/13B 2.51KB/s 

$ mscp -vv -n 4 test 10.0.0.1:
connecting to 10.0.0.1 for checking destinations...
file test/test.txt (local) -> ./test/test.txt (remote) 9B
file test/test2/2.txt (local) -> ./test/test2/2.txt (remote) 2B
file test/1.txt (local) -> ./test/1.txt (remote) 2B
connecting to 10.0.0.1 for a copy thread...
connecting to 10.0.0.1 for a copy thread...
connecting to 10.0.0.1 for a copy thread...
connecting to 10.0.0.1 for a copy thread...
copy start: test/test.txt
copy start: test/1.txt
copy start: test/test2/2.txt
copy done: test/test.txt
copy done: test/test2/2.txt
copy done: test/1.txt
[===============================================================] 100% 13B/13B 3.27KB/s

Note: mscp is still under development, and the author is not responsible for any accidents on mscp.