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Increases large file transfer rates by splitting the file into chunks, transferring them simultaneously via ftp or scp then recombining them

Project description

Splitcopy

Improves file transfer rates when copying files to/from JUNOS/EVO/Linux/BSD hosts.
It achieves this by splitting a file into chunks, transferring the chunks to the remote host and recombining them.

At a minimum, sshd must be running on the remote host.
On JUNOS/EVO this requires 'system services ssh' configuration.

If using ftp to copy files (default) then an ftp daemon must be running on the remote host.
On JUNOS this requires 'system services ftp' configuration.

Requires python 3.4 to run, recommend using 3.6+ for improved speeds.

install required module dependencies via:

python3 -m pip install junos-eznc

Script overheads include authentication, sha1 generation/comparison, disk space check, file split and join.
It can be slower than normal ftp/scp for small files as a result.

Because it opens a number of simultaneous connections, if the JUNOS/EVO host has connection/rate limits configured like this:

system {
    services {
        ssh { # or ftp
            connection-limit 10;
            rate-limit 10;
        }
    }
}

The script will deactivate these limits so it can proceed, then activate them again.

Arguments

filepath Mandatory, path to the src file you want to copy
userhost Mandatory, username and host to connect to, in format user@host
--pwd Optional, password to auth with. If you'd rather not have the password stored in shell history, you can omit this and it'll prompt you instead
--dst Optional, directory to put file. The default is /var/tmp/
--scp Optional, use scp instead of ftp to transfer files
--get Optional, copy from remote to local host

Example FTP transfer (default method)

$ ./splitcopy.py /var/tmp/jselective-update-ppc-J1.1-14.2R5-S3-J1.1.tgz lab@192.168.1.1
Password:
checking remote port(s) are open...
using FTP for file transfer
checking remote storage...
sha1 not found, generating sha1...
splitting file...
starting transfer...
10% done
20% done
30% done
40% done
50% done
60% done
70% done
80% done
90% done
100% done
transfer complete
joining files...
deleting remote tmp directory...
generating remote sha1...
local and remote sha1 match
file has been successfully copied to 192.168.1.1:/var/tmp/jselective-update-ppc-J1.1-14.2R5-S3-J1.1.tgz
data transfer = 0:00:16.831192
total runtime = 0:00:31.520914

Example SCP 'get' transfer

$ ./splitcopy.py /var/log/messages lab@192.168.1.1 --scp --get
Password:
checking remote port(s) are open...
using SCP for file transfer
checking remote storage...
generating remote sha1...
starting transfer...
10% done
20% done
30% done
40% done
50% done
60% done
70% done
80% done
90% done
100% done
transfer complete
joining files...
deleting remote tmp directory...
generating local sha1...
local and remote sha1 match
file has been successfully copied to /var/tmp/messages
data transfer = 0:00:18.768987
total runtime = 0:00:44.891370

Notes on using FTP

FTP is the default transfer method.
FTP progress on --get operations is supported from py-junos-eznc v2.2.2

The version of Python used has a big impact.
If using < 3.6 the maximum number of simultaneous transfers is 5.
If using 3.6+ it will allow 5 simultaneous transfers per cpu

Using FTP method will generate the following processes on the remote host:

  • for mgmt session: 1x sshd, 1x cli, 1x mgd, 1x csh
  • for transfers: up to 40x ftpd processes (depends on Python version and number of cpus as described above)

In theory, this could result in the per-user maxproc limit of 64 being exceeded:

May  2 04:46:59   /kernel: maxproc limit exceeded by uid 2001, please see tuning(7) and login.conf(5).

The script modulates the number of chunks to match the maximum number of simultaneous transfers possible (based on Python version and number of cpus).
The maximum number of user owned processes that could be created is <= 44

Notes on using SCP

The version of Python used has a big impact.
If using < 3.6 the maximum number of simultaneous transfers is 5.
If using 3.6+ it will allow 5 simultaneous transfers per cpu

Using SCP method will generate the following processes on the remote host:

  • for mgmt session: 1x sshd, 1x cli, 1x mgd, 1x csh
  • for transfers: depends on Python version, number of cpus (see above) and Junos FreeBSD version (see below)

In FreeBSD 10 based Junos each scp transfer creates 2 user owned processes and 1 root owned process:

root 28626   0.0  0.0   63248   5724  -  Ss   11:59AM     0:00.11 sshd: labroot@notty (sshd)
lab  28639   0.0  0.0  734108   4004  -  Is   12:00PM     0:00.01 cli -c scp -t /var/tmp/splitcopy_jinstall-11.4R5.5-domestic-signed.tgz/
lab  28640   0.0  0.0   24768   3516  -  S    12:00PM     0:00.01 scp -t /var/tmp/splitcopy_jinstall-11.4R5.5-domestic-signed.tgz/

In FreeBSD 6 based Junos each scp transfer creates 3 user owned processes:

lab  78625  0.0  0.1  2984  2144  ??  Ss    5:29AM   0:00.01 cli -c scp -t /var/tmp/splitcopy_jinstall-11.4R5.5-domestic-signed.tgz/  
lab  78626  0.0  0.0  2252  1556  ??  S     5:29AM   0:00.00 sh -c scp -t /var/tmp/splitcopy_jinstall-11.4R5.5-domestic-signed.tgz/  
lab  78627  0.0  0.1  3500  1908  ??  S     5:29AM   0:00.01 scp -t /var/tmp/splitcopy_jinstall-11.4R5.5-domestic-signed.tgz/  

In theory, this could result in the per-user maxproc limit of 64 being exceeded:

May  2 04:46:59   /kernel: maxproc limit exceeded by uid 2001, please see tuning(7) and login.conf(5).

The script modulates the number of chunks to match the maximum number of simultaneous transfers possible (based on Python version, number of cpus and Junos FreeBSD version).
The maximum number of user owned processes that could be created is <= 44

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