Hello && Welcome
Could you explain in greater detail about this? I was going to say just delete it, but you probably want to save some logs.
Are you looking for a full upgrade or creating a new Graylog server?
If your going to create a new host, were you thinking about transporting old log to the new server?
You could stop your INPUTs and let Graylog finish ingesting the log/s in the Journal.
“The Graylog journal is the component sitting in front of all message processing that writes all incoming messages to disk. Graylog then reads messages from this journal to parse, process, and store them. If anything in the Graylog processing chain, from input parsing, over extractors, stream matching and pipeline stages to Elasticsearch is too slow, messages will start to queue up in the journal.”
Hope that helps