How to create server backups with rsync

Backup copies should play an important role in your server planning. Individual backups can be set up and performed quickly using the free synchronisation tool or the rsync protocol.

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How to set up rsync backups on Linux servers

To use rsync on Linux operating systems, install the protocol in the package with the same name and create your backups using terminal commands. In the following section, we will use Ubuntu to show you the most important steps for setting up backup processes using rsync. We’ve also included practical examples as well.

Rsync is already installed in Ubuntu by default. If this is not the case, use the following command to install it:

sudo apt-get install rsync

If rsync is installed, you can use terminal commands to specify the source and destination directories and the backup options. The respective source directory and the directory where rsync should store the backup copy must be specified as the source and destination paths. The standard mode (‘Archive’) is executed as follows, for example:

rsync -a source directory target directory

Use the test run -n to check the correctness of the specified parameters and directories. Incorrect entries can, in the worst case, lead to data loss. If some files are not copied as they should be, this is often due to a lack of access rights. If this happens, try executing the command as an administrator with sudo in front of it.

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Five examples for using rsync backup

Once you know the fundamental commands, rsync is an outstanding tool for copying files and creating backups. You can either test and apply individual command setups or use proven combinations of the available rsync parameters. We have summarised five popular ways to carry out rsync backups in the following sections.

Standard backup with archive mode

The archive mode copies all files from the source directory to the target directory including all subdirectories. All authorisations, time stamps and device data are retained. This is the ideal and simplest solution in many cases as it combines various options in a single parameter. If you combine the mode with the -v parameter, you will also receive comprehensive status information during the backup process.

rsync -av Source directory Target directory

The respective source directory and the directory in which rsync should store the backup copy must be specified as the source and target path.

Identical copy of the source directory

Not only can rsync transfer files from A to B, it can also make identical copies of folders or entire directories. After standard archival, the files that were in the target folder before the rsync backup took place (but are not in the source folder) are deleted.

rsync -av --delete Source directory Target directory

rsync backup excluding files of a specific format

If you want to run an rsync backup excluding files in a specific format, you can use the --exclude command to do so. The parameter allows you to define an individual character pattern that rsync uses as an indicator to ignore a file. The following sample code excludes .txt files.

rsync -av --exclude'*.txt' Source directory Target directory

Backing up files with a minimum or maximum size

If, instead of a specific character pattern, you want the file size to influence the exclusion of specific files in an rsync backup, you can use the --max-size and --min-size parameters. If you use the following command, only files ranging from at least 10 MB to at most 100 MB are copied:

rsync -av --min-size=10MB --max-size=100MB Source directory Target directory

Backup including character format conversion

You may have to convert files into a different character format in the target directory. If you want to transfer data from a Mac to a Linux server, for example, you’ll want to include character format conversion. Apple devices use UTF8-MAC by default, which is not available on Linux systems and would cause problems with special characters. The --iconv option lets you easily adapt the character encoding as part of the rsync backup process (in the example below, from UTF8-MAC to UTF8):

rsync -av --iconv=UTF8-MAC,UTF8 Source directory Target directory

Overview of the most important rsync backup options

You can define the individual settings for your rsync backups using the different options, which can be abbreviated by letter or written out in full. The following table summarises the most important parameters, which can be combined with each other as required:

Option Function
-r, --recursive rsync backup takes all subdirectories into account
-u, --update Instruction to skip files in the target directory that are newer than those in the source directory
-c, --checksum Distinguish source and target files based on checksums
-l, --links Symbolic links are copied as such (and not as files)
-p, --perms File permissions are retained
-g, --group Group file permissions are retained
-t, --times File time stamps (last change) are retained
-o, --owner File owners are retained (only if administrators)
-D, --devices Device data is retained
-z, --compress Automatic compression of the transferred files
--compress-level=NUM Determines the compression level; values (‘NUM’) between 0 (no compression) and 9 (maximum compression) are possible
-v, --verbose More comprehensive details during the backup processes
-q, --quiet Hide all details on the backup process (except error messages)
-a, --archive Archive mode used as standard mode and identical to the option combination — rlptgoD
-n, --dry-run Test run in which no actual changes are made
-h, --help Auxiliary menu (can only be used without indicating source and target directories or other arguments)
--bwlimit=KBPS Restrict bandwidth (kilobytes per seconds); e.g. --bwlimit=30 (limit of 30 kbit/s)
--exclude=SAMPLE Exclude a pattern from synchronisation; e.g. --exclude sample folder (the ‘sample folder’ folder is not synchronised.)
--delete Delete all files that are in the target directory but not in the source directory
--progress Show the duration of the rsync backups and the transfer speed
--list-only List files instead of a backup
--stats Comprehensive report on the transferred data (number, size)
--max-size=SIZE Define a maximum file size; e.g. --max-size=10MB (only files with a size up to 10 MB are transferred.)
--ignore-errors Prevent cancellation of the backup process in the event of an error
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