Currently I am monitoring 10 hosts. I want to write a script which will calculate the disk space in every 24 hours and then if the file system of a host is critical for any host then it will move the old files from that host to the host which has the largest disk space?


There exist parallel ssh wrappers -- here are a few I found on CentOS7/EPEL:

    Name        : pssh
    Repo        : epel/x86_64
    Summary     : Parallel SSH tools
    URL         : http://code.google.com/p/parallel-ssh/
    License     : BSD
    Description : This package provides various parallel tools based on ssh and scp.
                : Parallell version includes:
                :  o ssh : pssh
                :  o scp : pscp
                :  o nuke : pnuke
                :  o rsync : prsync
                :  o slurp : pslurp

    Name        : pdsh
    Repo        : epel/x86_64
    Summary     : Parallel remote shell program
    URL         : https://pdsh.googlecode.com/
    License     : GPLv2+
    Description : Pdsh is a multithreaded remote shell client which executes commands
                : on multiple remote hosts in parallel.  Pdsh can use several different
                : remote shell services, including standard "rsh", Kerberos IV, and ssh.

    Name        : mpssh
    Repo        : epel/x86_64
    Summary     : Parallel ssh tool
    URL         : https://github.com/ndenev/mpssh
    License     : BSD
    Description : mpssh is a parallel ssh tool. What it does is connecting to a number of hosts
                : specified in the hosts file and execute the same command on all of them

So you could use that script to query the remote systems over ssh to get their disk space, and then evaluate which to clean up, and which to use as a destination.


This will run a script on the specified list of hosts in parallel:

declare -a CLEANUP
for host in host1.example.com host2.example.com; do # the list can be as long as you need
   ssh "$host" '/path/to/script' > "$OUTPUT" &
trap 'rm -fr "${OUTPUT[@]}"' EXIT
# How to parse the output files is an exercise I leave to you

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