Cloning and Backing up a Linux based System via Network

From TechnologicalWiki

Let's explain our situation:

We have a local linux based sytem, which name is LocalBox.

Our plan is to back up this system in a second machine, named SecondBox, and on the fly clone our local system in a third box called ThirdBox.

First of all we calculate the space we need to make the backup.

In LocalBox we type:

$df -h

Filesystem    Size   Used   Avail  Mounted
/dev/sda2     9.4G   3.9G   5.2G   /
/dev/sda3     98G    228M   93G    /home

/dev/sda2 is mounted as root and its size is less than 4 Gigabyte, and when compressed will have a minor size.

home partition has a very small size.

Our estimation is a less than 4 GB size backup needed.

Next step is to seek which filesystems are important for our backup and avoid all virtual filesystems.

$mount

/dev/sda2   on   /      type   ext3
proc        on   /proc  type   proc
sysfs       on   /sys   type   sysfs
debugfs     on   /sys/kernel/debug  type  debugfs
udev        on   /dev   type   tmpfs
devpts      on   /dev/pts   type    devpts
/dev/sda3   on   /home  type   ext3
securityfs  on   /sys/kernel/security   type securityfs

/root filesystem will be base directory for our backup.

/proc and /sys will be excluded because they are virtual system directories.

/dev is a virtual directory to store devices, created by udev.

/tmp is where temporary files are stored, will be excluded too.

We are interested only in the base system, so /media and /mnt will also be excluded.

Tar is the tool we use to perform the backup and data will be sent over the network using netcat command. See (3) line.

(3)LocalBox#tar cvjpf - --same-owner --exclude=/proc/* --exclude=/media/* --exclude=/dev/* --exclude=/mnt/* --exclude=/sys/* --exclude=/tmp/* --exclude=./error.log / 2>./error.log | netcat 10.100.100.22 6666

In SecondBox netcat will listen to 6666 port, save data in Backup.tbz file and resend it over the network through 7777 port.

(2)SecondBox$nc nc -l -p 6666 | tee Backup.tbz | nc 10.100.100.29 7777

We previously prepare a partition where we are going to clone our system. e.g: /dev/hda7

ThirdBox#mkfs.ext3 -b 4096 -L SuseClon /dev/hda7
ThirdBox#mount /dev/hda7 /mnt

And in the end ThirdBox listens to 7777 port and restores LocalBox system in /mnt where /dev/hda is mounted.

(1)ThirdBox#nc -l -p 7777 | tar xvjf - -C /mnt

VERY IMPORTANT NOTE:

(1) should be executed first, then (2) and latest (3)