Upgrade from ES 1.7 to ES 2.4 leads to loss of data

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?

The folder under "nodes" folder -

It means that you started 2 nodes at the same time on the same machine.

In 5.0 this is not possible anymore BTW.

Thanks! We ensured in our code that we wait for ES 1.7 uninstall to complete before installing ES 2.4. I'll check the same again. Also, do we need to wait for anything in particular when we say ES 1.7 is indeed uninstalled?

Did you run a ps -ef ?

I mean that elasticsearch 2.4 seemed to think that node 0 dir was locked by another instance.

I see, thanks

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