We have moved from ES 1.7 to ES 2.4 over a period of last 1 year in all our ES clusters. What we observed in some of our 1-node cluster is while upgrading from ES 1.7 to ES 2.4, all indices and aliases are gone. The steps (in simplified words) for upgrade are -
- Stop ES 1.7
- Uninstall ES 1.7
- Install ES 2.4 pointing to same data folder as ES 1.7
- Start ES 2.4
On further investigations, we noticed the data (from ES 1.7) was in [cluster name / nodes / 0] folder while the ES 2.4 is storing the data in [cluster name / nodes / 1] folder.
Any idea when this can happen and how to fix this issue?