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How To Start the Rsync Daemon for Continuous Directory Synchronization Between Two Servers

Ubuntu 10

In this article, we will delve into the process of setting up the rsync daemon for continuous directory synchronization between two servers. This is an essential procedure for system administrators who need to ensure that files and directories are mirrored across different servers.

Quick Answer

To start the Rsync daemon for continuous directory synchronization between two servers, you need to configure the Rsync daemon on the server hosting the directory you want to synchronize. This involves creating a configuration file, setting up authentication, and enabling the Rsync daemon. Once set up, you can use the Rsync command to synchronize the directories between the servers.

Introduction to Rsync

Rsync is a powerful tool that provides fast, incremental file transfer and synchronization between different hosts. It can significantly improve file transfer speed and efficiency by only sending the changes in the files instead of sending whole files every time.

Setting Up the Rsync Daemon

To start, we need to set up the rsync daemon on the server that hosts the directory you want to synchronize (server A). This daemon will allow the other server (server B) to connect and synchronize the directory.

Step 1: Configuration of Rsync Daemon

On server A, create a file named rsyncd.conf in the /etc directory. This file will contain the configuration for the rsync daemon. Here’s an example of what it might look like:

uid = rsync
gid = rsync
use chroot = no
pid file = /var/run/rsyncd.pid

[share]
 comment = share
 path = /etc/dirtosync
 read only = false
 list = yes
 hosts allow = *
 auth users = rsync
 secrets file = /etc/rsyncd.secrets

In this configuration:

  • uid and gid specify the user and group ID that the daemon will run as.
  • use chroot specifies whether the daemon should use chroot to sandbox the rsync process.
  • pid file specifies the location where the daemon will write its process ID.
  • [share] is the name of the share that will be accessible to server B.
  • path is the directory that will be shared.
  • read only specifies whether the share should be read-only.
  • list specifies whether the share should be listed when the client requests a list of shares.
  • hosts allow specifies which hosts are allowed to access the share.
  • auth users specifies which users are allowed to access the share.
  • secrets file specifies the file that contains the usernames and passwords for authentication.

Step 2: Creating the Secrets File

Next, create a file called rsyncd.secrets in the /etc directory with the following content:

rsync:rsync

This file contains the usernames and passwords for authentication. The format is username:password.

Step 3: Setting Permissions

Ensure that the rsync daemon has the necessary permissions. You can set the owner and group of the directory /etc/dirtosync to rsync using the following command:

chown rsync:rsync /etc/dirtosync

Step 4: Enabling the Rsync Daemon

On server A, edit the file /etc/default/rsync and set the value of RSYNC_ENABLE to true. This will enable the rsync daemon to start at boot.

Step 5: Starting the Rsync Daemon

You can start the rsync daemon on server A using the command:

/etc/init.d/rsync start

Synchronizing Directories

With the rsync daemon set up on server A, you can now synchronize the directory from server A to server B.

The command to do this on server B is:

rsync -avzr rsync@<serverA>:/etc/dirtosync/* /etc/dirtosync/

In this command:

  • -a stands for “archive”, which preserves permissions, ownerships, and timestamps, and recurses into subdirectories.
  • -v stands for “verbose”, which provides detailed information about the files being transferred.
  • -z stands for “compress”, which compresses the data before sending it.
  • -r stands for “recursive”, which copies directories recursively.

Continuous Synchronization

The command above will only synchronize the files once. To continuously synchronize the files, you can set up a cron job on server B to run the rsync command at regular intervals.

For example, you can create a cron script in /etc/cron.daily that contains the rsync command. This will run the rsync command once a day.

Conclusion

Setting up the rsync daemon for continuous directory synchronization between two servers can be a complex task, but it’s an essential skill for any system administrator. By following the steps outlined in this article, you should be able to set up the rsync daemon and synchronize directories between two servers.

What is the purpose of the rsync daemon?

The rsync daemon is used to facilitate continuous directory synchronization between two servers by allowing them to connect and transfer only the changes in files instead of sending the entire files.

How does rsync improve file transfer efficiency?

Rsync improves file transfer efficiency by sending only the changes made to files instead of sending the whole file. This significantly reduces the amount of data that needs to be transferred, resulting in faster synchronization.

Where should the rsync daemon configuration file be created?

The rsync daemon configuration file, rsyncd.conf, should be created in the /etc directory on the server that hosts the directory you want to synchronize.

How can I enable the rsync daemon to start at boot?

To enable the rsync daemon to start at boot, you need to edit the file /etc/default/rsync and set the value of RSYNC_ENABLE to true.

What permissions should be set for the directory to be synchronized?

The owner and group of the directory to be synchronized should be set to rsync using the chown command. For example: chown rsync:rsync /etc/dirtosync.

How can I synchronize directories between server A and server B?

To synchronize directories between server A and server B, you can use the command: rsync -avzr rsync@<serverA>:/etc/dirtosync/* /etc/dirtosync/. This command will copy the files from server A to server B.

How can I set up continuous synchronization between server A and server B?

To set up continuous synchronization, you can create a cron job on server B that runs the rsync command at regular intervals. For example, you can create a cron script in /etc/cron.daily that contains the rsync command to run it once a day.

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