RSync is a computer program which synchronizes files and directories from one location to another while minimizing data transfer using delta encoding when appropriate. An important feature of rsync not found in most similar programs/protocols is that the mirroring takes place with only one transmission in each direction.

The bottom line is that it kicks ass for automated backups, either on the local LAN or remotely over the internet. It does such a good job over remote connections because it only sends the changes, not the changed files, but just the changes to the files. Let's say you had a very large text file and all you did was add a period to the very end of the file, only that one period character is sent when you sync the backup.

Because of this bandwidth saving design I use it for server backups of several hundred gig of data. The web server only takes about a minute to sync its backup.

RSync can either push or pull the data, but I'll detail a scenario where there is a central RSync server to receive the backup data with multiple clients pushing their data backups. My following examples use the same PC for both the server and client.

RSync Server Setup

On the eComStation or OS/2 machine that will act as the server I have created a directory C:\backup

Download rsync from Paul Smedleys' site at http://smedley.info/os2ports/rsync.html and extract the file "rsync.exe" to the C:\backup directory

In that directory I created a file called "rsyncd.conf" containing the text:

max connections = 6
timeout=600

lock file = /var/rsyncd.lock
log file = /var/rsyncd.log
pid file = /var/rsyncd.pid

[backup]
comment = backup storage area
path = /backup
read only = false
list = yes
gid = root
uid = root

Now we can start up the rsync daemon process.

Open a command prompt and change to the C:\backup directory and execute the following command:

rsync --daemon --config="rsyncd.conf" --no-detach

You'll want that in a batch file for regular use.

To test that the daemon is up and running properly open another command prompt, change to the C:\backup directory and execute the command:

rsync localhost::

The response should look like this:

[C:\backup]rsync localhost::
backup              backup storage area

[C:\backup]

The server is ready to accept data.

Pushing the client data to the RSync server

For my example here I'll run a backup of my C:\HOME and C:\VAR directories and push the data to the locally running rsync server by executing this command from the c:\backup directory:

rsync -vru --delete /home /var localhost::backup/ecs_workstation/

The -vru tells it that I want

-v = verbose output

-r = to copy directories recursively

-u = update

The --delete tells it to remove files on the server end that have been deleted on the client end.

Note that it does accept multiple sources directories. (in unix style paths).

After running this, my C:\backup directory now contains the subdirectory "ecs_workstation" with copies of my home and var directory.

Further runs of rsync will be far faster since it will only be updating changes.

^piggy^