just out of curiosity while tinkering out a setup: How destructive is it to completely loose an Elasticsearch instance for Zammad after e.g. half a year in production?
Is all fine again by setting up a new Elasticsearch instance and then just re-index things with zammad run rake searchindex:rebuild (after adapting the config pointing to the new instance)? Or does one need to take care about ES backups?
If the elasticsearch only holds Zammads data, you can ignore backing it up.
The searchindex-rebuild will rebuild the whole Searchindex from zero, however, keep in mind that this can take fairly some time on bigger systems which slows down your installation during rebuilding.