解決Elasticsearch索引只讀（read-only）

原因為：es 的設置默認是 85% 和 90 %，95%

當為85%時：Elasticsearch不會將碎片分配給磁盤使用率超過85%的節點（ cluster.routing.allocation.disk.watermark.low）

當為90%時：Elasticsearch嘗試重新分配給磁盤低於使用率90%的節點（cluster.routing.allocation.disk.watermark.high）

當為85%時：Elasticsearch執行只讀模塊（cluster.routing.allocation.disk.watermark.flood_stage）

1、擴大磁盤或者刪除部分歷史索引

2、重置改只讀索引快

某一個索引重置只讀模塊
PUT /twitter/_settings
{
  "index.blocks.read_only_allow_delete": null
}
所有索引重置只讀模塊

PUT /_all/_settings { "index.blocks.read_only_allow_delete": null }

PUT /_cluster/settings
{
  "persistent" : {
    "cluster.blocks.read_only" : false } }

修改默認設置

可以修改為具體的磁盤空間值，也可以修改為百分之多少
臨時修改
PUT _cluster/settings
{
  "transient": {
    "cluster.routing.allocation.disk.watermark.low": "100gb",
    "cluster.routing.allocation.disk.watermark.high": "50gb",
    "cluster.routing.allocation.disk.watermark.flood_stage": "10gb",
    "cluster.info.update.interval": "1m"
  }
}
永久修改
PUT _cluster/settings
{
  "persistent": { "cluster.routing.allocation.disk.watermark.low": "100gb", "cluster.routing.allocation.disk.watermark.high": "50gb", "cluster.routing.allocation.disk.watermark.flood_stage": "10gb", "cluster.info.update.interval": "1m" } }

轉載自：https://www.elastic.co/guide/en/elasticsearch/reference/6.8/disk-allocator.html