Ygtjki

I want to do the following - Save the current state of my linux OS(centOS6.5). Do some changes (more specifically inject a fault and test some service to check how it behaves when that particular type of a fault occurs.) Then restore the system back to the saved state. I am not able to figure out how to do this on a linux system. I have a machine with centOS 6.5 with an ext4 filesystem.Also this is a physical server and not a virtual machine.

Any ideas or suggestions?

I would keep it simple and clone it. Boot a live system from USB (easiest is Ubuntu from a USB thumb drive, I find), then dump your hard disk to a different partition (or external hard drive etc.), e.g.

dd if=/dev/sda1 bs=64M of=/mnt/my_mounted_backup_drive/backup-sda1

where you need to replace /dev/sda1 with your root (/) partition. Do the same with other partitions (like the one for /boot, /boot/efi, /home) where applicable.

If you need to save space, you could do

dd if=/dev/sda1 bs=64M | gzip --fast | dd bs=32M of=/mnt/my_mounted_backup_drive/backup-sda1.gz

or, more complicated, much slower but saving a few more bytes,

mkdir -p /mnt/linux
mount -o ro /dev/sda1 /mnt/linux
cd /mnt/linux
tar cvJf /mnt/my_mounted_backup_drive/linux-backup.tar.xz .??* *

You can then restore the other way around, e.g.

mkdir -p /mnt/linux
mount /dev/sda1 /mnt/linux
cd /mnt/linux
tar xvJf /mnt/my_mounted_backup_drive/linux-backup.tar.xz

or

dd /mnt/my_mounted_backup_drive/backup-sda1.gz bs=32M | gzip --decompress | dd bs=64M of=/dev/sda1

(careful where you are writing your data, this deletes everything on /dev/sda1, so get it right the first time :-)

You can use rsync to backup the entire system.

rsync -aAXv --exclude="/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found" /* /path/to/backup/folder

There's a awesome article at Arch Linux Wiki about it

How about using rsync or rsnapshot to essentially backup the local machine? Once you test is done, simply restore the backup.

http://rsnapshot.org/

http://www.mikerubel.org/computers/rsync_snapshots/

Similarly, you can use LVM:

http://www.tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html

You can use FSArchiver, which will save the contents of the file system to a compressed file and restore the filesystem when extracting the data.

Here is an example from the documentation:

fsarchiver savefs /mnt/backup/gentoo-rootfs.fsa /dev/sda1

You can also use multi-threaded compression, and restoring is straightforward:

fsarchiver restfs /mnt/backup/gentoo-rootfs.fsa id=0,dest=/dev/sda1

In order to go back to a previous state, you could mount the current file system to a new directory. This mounts the file system to a new root directory specified by the following command:

mount DIR DIR

To restore this state, change the root of the file system from the directory specified in the mount command.

umount DIR