Using ElasticSearch as a permanent storage
I recommend you reading this old but still valid article : https://www.elastic.co/blog/found-elasticsearch-as-nosqlKeep in mind, Elasticsearch is only a search engine. But it depends if your data are critical or if you can accept to lose some of them like non critical logs.If you don't want to use an additionnal database with huge large data, you probably can store them into files in something like HDFS.
You should also check Phoenix https://phoenix.apache.org/ which may provide the monitoring features that you are looking for