Elasticsearch "READ ONLY" Indices

[tusharnemade]

Hello Team:

I am using Elasticsearch version 7.8.0..

I am using Index Settings :

index.blocks.read_only_allow_delete: true for my indices ...

If i run a CURL command to update my index settings

curl -X PUT "localhost:9200/my-index-000001/_settings?pretty" -H 'Content-Type: application/json' -d'
{
  "index" : {
    "refresh_interval" : "-1"
  }
}
'

1. Operation is perform successfully
2. It removed my existing Index settings of "index.blocks.read_only_allow_delete: true "

could you please help me to understand why is this behaviour.

[DavidTurner]

The docs for index.blocks.read_only_allow_delete say:

IMPORTANT: Elasticsearch adds and removes the read-only index block automatically when the disk utilization falls below the high watermark.

[tusharnemade]

Hi David

I did read the doc , before raising it in here ..

I am not having DISK utilization issue .. i am having ample amount of space.

its automatically removed when i am adding above said settings for my index.

[tusharnemade]

Let me put an example in here ...

My Index Settings :

{
  "myindex-2020.02.19" : {
    "settings" : {
      "index" : {
        "codec" : "best_compression",
        "routing" : {
          "allocation" : {
            "require" : {
              "box_type" : "warm"
            }
          }
        },
        "number_of_shards" : "5",
        "blocks" : {
          "read_only_allow_delete" : "true"
        },
        "provided_name" : "myindex-2020.02.19",
        "creation_date" : "1628563570323",
        "number_of_replicas" : "1",
        "uuid" : "DmhmKaqnS1mjfBs5fpNX7Q",
        "version" : {
          "created" : "7080099"
        }
      }
    }
  }
}

Now I am changing particualr settings only :

curl -X PUT "localhost:9200/myindex-2020.02.19/_settings?pretty" -H 'Content-Type: application/json' -d'
{
    "index" : {
        "refresh_interval" : "-1",
        "number_of_replicas" : 0
    }
}' -u elastic

{
  "acknowledged" : true
}

Now see the setting of READ ONLY is gone ...

curl -XGET "localhost:9200/myindex-2020.02.19/_settings?pretty" -u elastic
{
  "myindex-2020.02.19" : {
    "settings" : {
      "index" : {
        "codec" : "best_compression",
        "routing" : {
          "allocation" : {
            "require" : {
              "box_type" : "warm"
            }
          }
        },
        "refresh_interval" : "-1",
        "number_of_shards" : "5",
        "provided_name" : "myindex-2020.02.19",
        "creation_date" : "1628563570323",
        "number_of_replicas" : "0",
        "uuid" : "DmhmKaqnS1mjfBs5fpNX7Q",
        "version" : {
          "created" : "7080099"
        }
      }
    }
  }
}

[DavidTurner]

Quoting those docs again with emphasis added:

@DavidTurner

Elasticsearch adds and removes the read-only index block automatically

This looks like the expected behaviour to me.

[tusharnemade]

So its like whenever we change Index settings , its likely and expected that READ ONLY settings would be removed .. irrespective of DISK UTILIZATION issue...

That is that you are Emphasising ?

[DavidTurner]

Yes that's right.

[tusharnemade]

Thank You @DavidTurner