Transfer TB of files in the background via rsync and tmux on linux

## Problem

Transfering files in the background via `rsync` is possible via `nohup` command and some other workarounds. 

These don't really work when your transfer takes days (>50TB of data) because the background job might get killed by the system.

In order to create a persistent session we need to use `tmux`.

## Solution

### Authentication
Create a ssh key and upload it to the server you want to transfer from.

```bash
ssh-keygen -t ed25519
ssh-copy-id -i ~/.ssh/id_rsa.pub [your_old_server.domain.com]
```

### Create a new session and run `rsync`

```bash
tmux new -s [your_session_name]

rsync --avhPW --stats [your_old_server.domain.com]:[/source/path/] [/destination/path]
```

### Detach from session


Press `CTRL+B` and then `D`. You session will detach and run in background.


### Re-attach session

To get back into your session just:

```bash
tmux a -t [your_session_name]
```

That's it.

Zeno Popovici
30 Jan 2024