Data Transfer

Pros

The Pros of this approach include:

• SCP is known for its security and reliability.
• SCP provides strong authentication and encryption, which means only authorized users can access and transfer the files.
• SCP also uses TCP, which means it has error detection and recovery mechanisms, which means the transfer can resume or restart if there is network problems.

Cons

The Cons of this approach include:

• SCP has its own complexity and overhead.
• SCP can be slower and more resource-intensive than TFTP, especially over long distances or congested networks. It also requires more configuration and maintenance on both the router and the server side, such as managing SSH keys and updating SSH software.

Limitation

Only one SCP client session is supported at a time

Licensing

Open Source

Pros

The Pros of this approach include:

• By default, it is on every six systems, so no messy installation is needed. rsync has not changed in a long time, so there is no need for feature and revision differences.
• The file system at the destination server inspects and syncs; this is an important factor to consider for easier failovers.
• Failing over and back to use is simple because this is all done at the file system level. If a server is to fall out of sync or if there is a need to add another server into replication, a simple rsync command catches things up.

Cons

• Data will never be as up to date as rsync is copied from an existing data source, and DRBD synchronous mode is to write to all servers before deeming it a successful commit.
• You need to write checks for validation and monitoring, as Rsync does not provide any of that.
• You need to figure out the exact flags and options. This is not a big con, as it is a one-time tax to be paid.

Limitation

• The rsync operation runs slowly against a file system. Cause: rsync is a serial operation, so it is slow when copying a large file system, especially if snapshots are included in the process.

Sample code

Users can also utilize wrapper script for rsync, which is available in the GitHub repo, click here Scenario

If you have a farm of NFS servers in production that needed replication 1) failover and 2) backup.

Licensing

Open Source

Pros

The Pros of this approach include:

• Powerful command line interface (CLI) - Free and open-source - Works with over 40 cloud storage services
• RClone is primarily used for backing up to cloud storage such as Google Drive or BackBlaze.
• RClone stores each file you transfer as a native object on the remote cloud storage system.
• RClone supports copy or sync commands.

Cons

The Cons of this approach include:

• Steep learning curve - No customer support - No cloud storage
• unidirectional sync from A to B

Limitations

• Rclone doesn't currently preserve the timestamps of directories. This is because rclone only really considers objects when syncing.
• Currently rclone loads each directory/bucket entirely into memory before using it. Since each rclone object takes 0.5k-1k of memory this can take a very long time and use a large amount of memory.
• Bucket-based remotes (e.g. S3/GCS/Swift/B2) do not have a concept of directories. Rclone therefore cannot create directories in them, which means that empty directories on a bucket-based remote tend to disappear.

Licensing

Open Source

To learn more about RClone, click here.

copy module

This ansible copy module copies files to remote locations.
The copy module copies a file from the local or remote system to a location on the remote system. Use the fetch module to copy files from remote locations to the local box. If you need variable interpolation in copied files, use the template module.
For Windows targets, use the win_copy module instead.

[replica_host]
<dr_host_ip> ansible_ssh_user=root ansible_ssh_private_key_file=/root/.ssh/id_rsa"

---
- name: Copy App Data to Replica
  become: yes
  hosts: replica_host
  tasks:
- name: Copy file from app to replica
  copy:
    src: /etc/app/app.conf
    dest: /etc/app/app.conf
    owner: appuser
    group: appuser
    mode: '0644'

ansible.builtin.copy module

This is the same as the copy module but uses the ansible.builtin.fetch module to copy files from remote locations to the local box. If you need variable interpolation in copied files, use the ansible.builtin.template module. Using a variable in the content field results in unpredictable output.

For Windows targets, use the ansible.windows.win_copy module instead.

---
- name: Copy App Data to Replica
  become: yes
  hosts: replica_host
  tasks:
- name: Copy file from app to replica
  ansible.builtin.copy:
    src: /etc/app/app.conf
    dest: /etc/app/app.conf
    owner: appuser
    group: appuser
    mode: '0644'

Ansible synchronize

Synchronize is a wrapper around rsync to make common tasks in your playbooks quick and easy. It is run and originates on the local host where Ansible is being run. You might use the command action to call rsync yourself, but you must also add a fair number of boilerplate options and host facts. Synchronize is not intended to provide access to the full power of Rsync, but it does make the most common invocations easier to implement. You may still need to call rsync directly via command or shell, depending on your use case.

---
- name: Copy App Data to Replica
  become: yes
  hosts: replica_host
  tasks:
- name: Copy file from app to replica
  ansible.builtin.copy:
    src: /etc/app/app.conf
    dest: /etc/app/app.conf
    owner: appuser
    group: appuser
    mode: '0644'