The only copy of the raw events is stored in the index, so in case of an ElasticSearch cluster failure/loss, the events will be lost.

There are various solutions in terms of backing up ES:

• ES Snapshots
• elasticdump
• Raw filesystem backups for each node... 🤢

In terms of managing indices it might be also worth taking a look into the Python library elasticsearch-curator.

(TODO: add some numbers from Invenio instances running invenio-stats for what's the estimated number of events/storage used)