There are many ways to backup Servers. One of the better ways to accomplish this is using rsnapshot. Rsnapshot is nothing but a filesystem snapshot utility for backing up local and remote systems.
Rsnapshot is written in Perl, and depends on rsync. With ssh access, it is possible to backup remote servers.
Why rsnapshot?
We have many familiar ways to generate full backup and copy it to
another server which includes ftp, scp and all. But now the question
that comes to your mind will be "Why should I use rsnapshot ? or What
is so special about this tool?"
Listed below are the major advantages of rsnapshot, which make you feel
that it is worth using.
- Using rsync and hard links, it is possible to keep multiple, full
backups instantly available. The disk space required is just a little
more than the space of one full backup, plus incrementals. This comes
as a criteria when your drive is lacking enough free space to
accommodate 3 copies of backup.
- Depending on your configuration, it is quite possible to set up
in just a few minutes. Files can be restored by the users who own them,
without the root user getting involved.
- There are no tapes to change, so once it's set up, you may never
need to think about it again.
- Rsnapshot takes advantage of hard links (multiple directory
pointers to the same data) to give the appearance of multiple full
backups yet requires only enough disk capacity to store the complete
data set plus any changed files. Thus we have the illusion of full
hourly, daily, weekly, and monthly backups without having the physical
space to hold that many copies.
- Another benefit is that rsync is cross-platform, so it isn't
constrained to *nix systems.
Installation of rsnapshot
Rsnapshot can be installed in a few minutes of time. It requires the
following prerequisites.
1) Perl
2) rsync
i). Download the latest source tarball from
http://www.rsnapshot.org/downloads.html
ii). Untar the source code package
tar xzvf rsnapshot-1.3.0.tar.gz
iii). Change to the source directory.
cd rsnapshot-1.3.0/
iv). Select the directory to install the files. Usually the files are
placed in /usr/local directory and the config files in the /etc
directory.
v). Run the configure script
./configure --sysconfdir=/etc
vi). Install the program by
make install
Now rsnapshot is installed under /usr/local, with the config file in
/etc.
Configuration
A sample copy of the rsnapshot config file is provided with the
package. We need to just copy the file.
cp /etc/rsnapshot.conf.default /etc/rsnapshot.conf
The directives that need to be configured in rsnapshot.conf
1. snapshot_root
This is the snapshot root directory which holds the file system
snapshots.
snapshot_root /.snapshots/
2. Modify the path to the various programs like rm for removing files,
rsync, ssh etc. Usually not much modification is needed here.
3. Specify thebackup intervals.
interval hourly 6
interval daily 7
interval weekly 4
In this example, rsnapshot is taken every four hours, or six times a
day (these are the hourly intervals), 7 times a week, 4 times a month.
Thus it covers the whole month (4 weeks)
4. Select verbose level, loglevel and logfile path. Typical values used
are
verbose 2
loglevel 3
logfile /var/log/rsnapshot
5. Next main configuration to be done is BACKUP POINTS / SCRIPTS
This is the section where you tell rsnapshot what files you actually
want to back up. You put a “backup” parameter first, followed by the
full path to the directory or network path you're backing up. The third
column is the relative path you want to back up to inside the snapshot
root.
# LOCALHOST
backup /home/ localhost/
backup /etc localhost/
backup /usr/local/ localhost/
For example, take case 1, where the parameter is "backup". We are
backing up the /home partition of the server on the rsnapshot root of
our server itself. Thus with this backup parameter, a backup of /home
is
created in /root/.snapshots
In addition to full paths on the same server, we can also backup
filesystems on remote systems using rsync over ssh. To get this done,
a) The ssh daemon must be running on the remote server.
b) You must have access to the account you specify the remote machine,
in this case the root user on remote server.
c) You must have key-based logins enabled for the root user at remote
server, without passphrases.
# EXAMPLE.COM
backup root@example.com:/home/ example.com/
backup root@example.com:/home/ example.com/ exclude=mtab,exclude=core
In example 1, /home partion of remote server example.com is backed up
to the server where snapshot is running. In example 2, similarly /etc
partion is backed up, excluding mtab and core directories.
This backup parameter is commonly used in live servers for backup
configuration.
Allowing remote logins with no passphrase is a security risk that may
or may not be acceptable in your situation. Make sure you guard access
to the backup server very carefully! If we wish to perform backup as
another user, we could specify the other user instead of root for the
source (i.e. user@example.com).
Now with this we have completed the basic configuration of rsnapshot.
6. Testing configuration file.
rsnapshot configtest
If all is well, it should say Syntax OK, or else the errors are shown.
We have to use tabs in the config file and not spaces.
7. Test run of rsnapshot
rsnapshot -t hourly
This tells rsnapshot to simulate an "hourly" backup. It will print out
the commands it will perform when it runs for real.
Automating rsnapshot using cron job
Edit root's crontab by command
crontab -e
Add the following entries,
0 */4 * * *
/usr/local/bin/rsnapshot hourly
30 23 * * *
/usr/local/bin/rsnapshot daily
Cron should be timed in a way that the hourly backup is finished before
performing the daily backup.
How it works
All backups are stored in the snapshot directory. New directories
inside the snapshot root are created when rsnapshot hourly and weekly
are run. Thus when rsnapshot hourly is run 6 times, the directories
with name hourly.0, hourly.1, ....hourly.5 are created. Similarly when
rsnapshot weekly is run, 7 new directories are created namely weekly.0,
weekly.1, weekly.2 till weekly.6.
Each subsequent time rsnapshot is run with the hourly command, it will
rotate the hourly.X directories, and then “copy” the contents of the
hourly.0 directory (using hard links) into hourly.1.
When rsnapshot daily is run, it will rotate all the daily.X
directories, then copy the contents of hourly.5 into daily.0.
hourly.0 will always contain the most recent snapshot, and daily.6 will
always contain a snapshot from a week ago.
Unless the files change between snapshots, the “full” backups are
really just multiple hard links to the same files.
That is how rsnapshot saves disk space. If the file changes at any
point, the next backup will unlink the hard link in hourly.0, and
replace it with a brand new file.
When weekly, monthly, and yearly intervals defined (in that order), the
weekly ones would get updated directly from the filesystem, the monthly
ones would get updated from weekly, and the yearly ones would get
updated from monthly.
Conclusion
When the aforesaid instructions are followed, rsnapshot installation is
quite simple and is very efficient in performing automatic backups of
your system. The amount of disk space taken up will be equal to one
full backup, plus an additional copy of every file that is changed.
Reference:
http://www.rsnapshot.org/
About the author: Sijin A. George works as Sr. Software Engineer (Grade II) in Bobcares.com.
She has worked in Bobcares for 3 years and specializes mainly on linux server administration.
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