Manual delete of specific index in data folder leads to all indexes deletion

Elastic Stack Elasticsearch
1

Hello,
I am asking this on behalf of a colleague.
He is using Elasticsearch 2.3.3 and they got an index corruption.
They decided to delete one folder representing the name of the index which was corrupted.
After that, they discovered no index was more present.

Some logs were mentioning:
java.lang.IllegalArgumentException: Could not load codec 'Lucene54'. Did you forget to add lucene-backward-codecs...

What would be the root cause of that?

2

I don't know why other indices disappeared, but it could be because you should never manually interact (delete, edit, move, etc.) with the files in the data directory. Indices should only ever be interacted with via the API, except in extreme cases which are so rare as to not apply in 99.999% of cases.

3

I completely agree with you.
Just wanted to ask how the deletion of index A could lead to deletion of ALL indices.

4

Probably metadata corruption.