我的Elasticsearch集群从2B文档下降到900M条记录，在AWS上显示

  

重定位碎片：4

显示

  

活动碎片：35

和

  

活动主分区：34

（可能不相关，但这是其余统计信息）：

  

节点数：9

     

数据节点数：6

     

未分配碎片：17

运行时

GET /_cluster/allocation/explain

它返回：

{
  "index": "datauwu","shard": 6,"primary": true,"current_state": "unassigned","unassigned_info": {
    "reason": "NODE_LEFT","at": "2019-10-31T17:02:11.258Z","details": "node_left[removedforsecuritybecimparanoid1]","last_allocation_status": "no_valid_shard_copy"
  },"can_allocate": "no_valid_shard_copy","allocate_explanation": "cannot allocate because a previous copy of the primary shard existed but can no longer be found on the nodes in the cluster","node_allocation_decisions": [
    {
      "node_id": "removedforsecuritybecimparanoid2","node_name": "removedforsecuritybecimparanoid2","node_decision": "no","store": {
        "found": false
      }
    },{
      "node_id": "removedforsecuritybecimparanoid3","node_name": "removedforsecuritybecimparanoid3",{
      "node_id": "removedforsecuritybecimparanoid4","node_name": "removedforsecuritybecimparanoid4",{
      "node_id": "removedforsecuritybecimparanoid5","node_name": "removedforsecuritybecimparanoid5",{
      "node_id": "removedforsecuritybecimparanoid6","node_name": "removedforsecuritybecimparanoid6",{
      "node_id": "removedforsecuritybecimparanoid7","node_name": "removedforsecuritybecimparanoid7","store": {
        "found": false
      }
    }
  ]
}

有点困惑，这到底是什么意思，这是否意味着我的Elasticsearch集群没有丢失数据，而是将其重新定位到了不同的分片中，还是找不到它？

如果找不到碎片，是否表示我的数据丢失了？如果是这样，可能是什么原因，我如何防止这种情况将来发生？

我没有建立副本，因为我正在索引数据，而副本在索引时会减慢速度。

也没有，我的记录数曾一度下降到400m，但随后又随机上升到900m。我不知道这意味着什么，任何见识将不胜感激。