Documents missing in index | Elastic 2.3

Hi,

I'm trying to find the root cause of an issue in my elasticsearch cluster. Recently my Elasticsearch went Red and from that day onwards I see that there are around 100M records missing from the index. I don't find any specific logs regarding this in the logs. Just that one of the node was removed from the cluster.

Any help to find the cause would be really helpful.

What is the size and configuration of the cluster? Do you have any indices that are red or yellow? Is there anything in the logs?