When indexing ~4000 documents (two vectors per document) with the _bulk update API to 12 different indices in elastic search a small number of indices are entering red state. Cluster resources (CPU and memory) do not seem stressed. Is there any advice that can be provided with regards to indexing vectors into multiple indices on the same cluster concurrently?
UPDATE: This is only occurring when we try writing to indices restored from a snapshot. Everything is fine if we rebuild the indices from scratch.