how to ensure no logs loss?

As known , in the production env the network disconect, disk I/O hang, some other hardware error makes the server not be avaiable. So how this tool works do not loss log data for these scenarios?
The suspected scenarios that may lead to data loss.
1. The net work between current openresty server and the remote server disconnect more than mintues/hours
2. The remote server disk I/O hang
3. A single remote server experiences a very severe failure, rendering the machine unavailable and inaccessible
Anyone know these scemarios, please help to answer