cloning.html

SlackWay

Focus on cloning & system disaster recovery with Slackware

Rsync is a remote synchronization tool. The first time, rsync sends all the data over the network to your backup machine. Just like tar. The benefit comes the next time you backup. Instead of sending all the files again, rsync only transfers files that have been changed. If no files were changed, no files get transferred. And when you want to recover data, you transfer just the specific files that you want back to your machine (using rsync or scp or telnet or whatever).

Why use rsync

Rsync can be used in many ways and is from far much better than imaging solution:
You could imagine using rsync to:

- synchronize data
- backup remote file systems
- clone your system
- preconfigured a linux desktop
- rsync to test file systems
- rsync to test kernels
......

rsync usage

rsync --force --ignore-errors --delete --delete-excluded --exclude-from=exclude_file --backup --backup-dir=`date +%Y-%m-%d` -av

Archive flag

Most of the time, rsync is used with -a (archive), which combines a number of other options:

-r recurse into subdirectories
-l copy symlinks as symlinks
-p retain file permissions
-t retain file time stamps
-g retain group ownership
-o retain owner
-D preserve devices

--backup: create backups of files before overwriting them
--backup-dir=`date +%Y-%m-%d`: create a backup directory for those backups which will look like this: 2002-08-15
-av: archive mode and verbose mode.

For a full list of rsync options, visit the rsync page.

And here some practical information about how a system can be secured & restored with rsync:

Cloning a system

This clones a running linux-system (really):

rsync -v -r -p -o -g -D -t -S -l -H \

--exclude /mnt/   \

--exclude /proc/ \

--exclude /tmp/ \

--exclude /home/ / /mnt/fireball/

The target-disk is /mnt/fireball in my case. We assume the target-disk is empty at the first time. My home is on a another disk, so i skip it . The options are:

--verbose

--recursive

--perms

--owner

--group

--devices

--times

--sparse

--links

--hard-links

# next time(s):

--delete

If you want to see first what happens, add:

--dry-run

Boot from a CD-ROM and mount the target-disk. Fix fstab and lilo.conf. Create /mnt and /proc and set the right permissions (for this directories). Then run lilo and reboot. Next time you run rsync, add these option to the command-line:

--exclude /etc/fstab \

--exclude /etc/lilo.conf \

--delete