If a shard goes down, then, after re-allocating that shard, will data residing in that shard be retrievable

Question

I have manually allocated 3 primary shards to a particular node in ElasticSearch. The replicas of these shards reside in different nodes. Now, let's say, primary shard number 2 goes down (for example, due to overflow of data) without the node on which it is residing going down. Then is it possible to retrieve the data residing on that particular shard, after I manually re-allocate it to a different node? If yes, how?

Answer 1

Yes.

Once the node with primary shard number 2 goes down then the replica shard on the other node will be upgraded to a primary shard - allowing you to retrieve the data. See here:

Coping with failure (ES Definitive Guide)