Inotify+unison implementation of data bidirectional synchronous backup in Linux

The servers are:
Server a:192.168.1.6, synchronizing directory:/var/www
Server b:192.168.1.7, synchronizing directory:/var/www

Install Unison
First install OCaml, version is at least 3.07 or higher
Download Address: http://caml.inria.fr

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Tar xvf ocaml-3.10.2.tar.gz CD ocaml-3.10.2 ./configure Make World opt Make install Cd..

Install Unison
Download Address: www.seas.upenn.edu/~bcpierce/unison/

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tar xvf unison-2.32.52.tar.gz CD unison-2.32.52 make Uistyle=text threads=true static=true CP Unison/usr/local/bin CD.. Note: Uistyle=text threads=true static=true represents the use of the command-line method, adding thread support to compile Install inotify in static mode download address: http:// Inotify-tools.sourceforge.net Tar xvf inotify-tools-3.14.tar.gz CD inotify-tools-3.14 ./configure Make Make install CD ...

Configure dual-machine SSH Trust (in addition to the following methods, you can also generate a key in a, the. ssh directory on A to the full SCP to B server/root/.ssh, so convenient)
Log in as root user
Create the. SSH directory on Server A
mkdir ~/.ssh
chmod ~/.ssh
Generate RSA Key
SSH-KEYGEN-T RSA
(then return three consecutive times)
Add encryption key to authorization key file
operation on 192.168.1.6 Server A (2222 is the port number)

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CD ~/.ssh SSH "-P 2222" 192.168.1.6 cat/root/.ssh/id_rsa.pub >> Authorized_keys #小写p SSH "-P 2222" 192.168.1.7 cat/root/.ssh/id_rsa.pub >> Authorized_keys Scp-p 2222 Authorized_keys 192.168.1.7:/root/.ssh/#大写P chmod 600/root/.ssh/authorized_keys

Operating on 192.168.1.7 Server B
chmod 600/root/.ssh/authorized_keys
Perform the following tests on both machines (when you first execute, you will be asked to enter a password and you won't need to explain the trust success later)

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Ssh-p 2222 192.168.1.6 Date Ssh-p 2222 192.168.1.7 Date

Add script
To add a script on 192.168.1.6 Server A:

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Mkdir/script vim/script/inotify.sh #/bin/bash Unison= ' ps-ef |grep-v grep|grep-c inotifywait ' If [${unison}-LT 1] Then Ip2= "192.168.1.7" Src2= "/var/www/" Dst2= "/var/www/" /usr/local/bin/inotifywait-mrq-e Create,delete,modify,move $SRC 2 | While Read line Todo /usr/local/bin/unison-batch $src 2 ssh://$ip 2/$DST 2 Echo-n "$line" >>/var/log/inotify/inotify$ (date +%u). log Echo ' Date +%f%T '-f1-4 ' >>/var/log/inotify/inotify$ (date +%u). log Done Fi

To add a script on the 192.168.1.7 server:

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mkdir/script vim/script/inotify.sh #/bin/bash unison= ' ps-ef |grep-v grep|grep-c inotifywait ' If [${unison}-lt 1 ] Then ip2= "192.168.1.6" src2= "/var/www/" dst2= "/var/www/" /usr/local/bin/inotifywait-mrq-e Create,delete,modify,move $SRC 2 | While the read line do /usr/local/bin/unison-batch $src 2 ssh://$ip 2/$DST 2 Echo-n "$line" >>/var/log/inot ify/inotify$ (date +%u). Log Echo ' date +%f%T '-f1-4 ' >>/var/log/inotify/inotify$ (date +%u). Log Done Fi

To modify script permissions on two servers:
chmod a+x/script/inotify.sh
Add a task to a scheduled task (originally added under/etc/rc.local, but the script does not execute)

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Crontab–e #unison +inotify * * * * * */bin/sh/script/inotify.sh >/dev/null 2>&1 &

Reboot the computer to test whether the contents of/var/www in two servers can be synchronized

Do not reboot the computer, the manual execution of the script can also test
Sh/script/inotify
When you add, modify, or delete files in one of the/var/www directories, you can see the script state while the other server should follow the action, and if there is a problem, please manually modify the script

In some companies, it is forbidden to disable root remote logging and only use normal users for synchronization scenarios
Waiting for sync directory (two computers can not use the same directory name to be synchronized, otherwise the error)

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192.168.1.6:/var/web1 192.168.1.7:/VAR/WEB2 installation process Useradd–g Apache Unison passwd Unison (Enter new password) Chown–r Unison. /var/www Mkdir/home/unison/.ssh chmod 700/home/unison/.ssh Su–unison SSH-KEYGEN-T RSA

(then return three consecutive times)

Add encryption key to authorization key file
operation on 192.168.1.6 Server A (2222 is the port number)

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Cd/home/unison/.ssh SSH "-P 2222" 192.168.1.6 cat/home/unison/.ssh/id_rsa.pub >> Authorized_keys #小写p SSH "-P 2222" 192.168.1.7 Cat/home/unison/.ssh/id_rsa.pub >> Authorized_keys Scp-p 2222 Authorized_keys 192.168.1.7:/home/unison/.ssh/#大写P chmod 600/home/unison/.ssh/authorized_keys Operating on 192.168.1.7 Server B chmod 600/home/unison/.ssh/authorized_keys

Perform the following tests on both machines (when you first execute, you will be asked to enter a password and you won't need to explain the trust success later)

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Ssh-p 2222 unison@192.168.1.6 Date Ssh-p 2222 unison@192.168.1.7 Date Su-root

A script:

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#/bin/bash unison= ' ps-ef |grep-v grep|grep-c inotifywait ' If [${unison}-lt 1] then ip2= "unison@192.168.1.7:222 2 " src2="/var/web1/" dst2="/var/web2/" /usr/local/bin/inotifywait-mrq-e create,delete,modify,move $src 2 | While the read line do /usr/local/bin/unison-batch-sshargs "-i/home/unison/.ssh/id_rsa" $SRC 2 ssh://$ip 2 /$DST 2 Echo-n "$line" >>/var/umelook-log/inotify/inotify$ (date +%u). Log Echo ' date +%f%T ' >>/var/umel ook-log/inotify/inotify$ (date +%u). Log Done Fi

B Script:

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#/bin/bash Unison= ' ps-ef |grep-v grep|grep-c inotifywait ' If [${unison}-LT 1] Then Ip2= "unison@192.168.1.6:2222" Src2= "/var/web2/" Dst2= "/var/web1/" /usr/local/bin/inotifywait-mrq-e Create,delete,modify,move $SRC 2 | While Read line Todo /usr/local/bin/unison-batch-sshargs "-i/home/unison/.ssh/id_rsa" $SRC 2 ssh://$ip 2 /$DST 2 Echo-n "$line" >>/var/umelook-log/inotify/inotify$ (date +%u). log Echo ' Date +%f%T ' >>/var/umelook-log/inotify/inotify$ (date +%u). log Done Fi

This is my own common use of synchronous backup is not this and a one-way backup tool, is the network more commonly used a backup tool, I will not say so that everyone attack me ah.