Elasticsearch is gone Red after delete index

[merceskoba]

This ES instance is in staging server but i am still curious to solve this case.
So, yesterday i deleted one index. And then, the server is red suddenly.
I am using Cerebro for understand it visually

743 unassigned shards with grey boxes.
What should i do ?
Thank you for your time and idea

[Christian_Dahlqvist]

As you only have one node in the cluster Elasticsearch will not be able to allocate replicas, which seem to account for at least a large portion of the unallocated shards. Unless you also have primary shards unallocated, this is not something to be concerned about.

You do however seem to have too many shards in your cluster given the node count and data volume, so I would recommend you read this blog post about shards and sharding guidelines.

[merceskoba]

I am also reading this RED Elasticsearch Cluster? Panic no longer | Elastic Blog
It seems enlightening me LOL
But, i got this after run /allocation/explain command

root@es-staging-10-255-13-51:~# curl -X GET "10.255.13.51:9200/_cluster/allocation/explain"?pretty
{
"index" : "-instagram-7-2018",
"shard" : 4,
"primary" : false,
"current_state" : "unassigned",
"unassigned_info" : {
"reason" : "CLUSTER_RECOVERED",
"at" : "2019-01-23T03:32:56.294Z",
"last_allocation_status" : "no_attempt"
},
"can_allocate" : "no",
"allocate_explanation" : "cannot allocate because allocation is not permitted to any of the nodes",
"node_allocation_decisions" : [
{
"node_id" : "b-bg1FkWQISXvyMyHZ2svQ",
"node_name" : "elastic-staging",
"transport_address" : "10.255.13.51:9300",
"node_decision" : "no",
"deciders" : [
{
"decider" : "same_shard",
"decision" : "NO",
"explanation" : "the shard cannot be allocated to the same node on which a copy of the shard already exists [[instagram-7-2018][4], node[b-bg1FkWQISXvyMyHZ2svQ], [P], s[STARTED], a[id=OpftlDlKRY2wEdi-nZEKyw]]"
}
]
}
]
}