Freezing an Index

Precautions

Before freezing an index, ensure no data is being written to it. The index will be set to read only before being frozen, and data write will fail.
After an index is frozen,
- It becomes read-only.
- The index data will be dumped to OBS. This process occupies network bandwidth.
- The query latency of a dumped index will increase. During aggregation, the latency of processing complex queries and reading a large volume of data is long.
- It cannot be unfrozen. That is, a read-only index cannot be changed to writable.
- After the freezing is complete, the index data in your local disks will be deleted.

Procedure

Log in to the CSS management console.
Choose Clusters in the navigation pane. On the Clusters page, locate the target cluster and click Access Kibana in the Operation column.
Click Dev Tools in the navigation tree on the left.

Run the following command to freeze a specified index and dump it to OBS:

POST ${index_name}/_freeze_low_cost

**Table 1** Parameter description
Parameter	Description
index_name	Name of the index to be frozen.

Information similar to the following is displayed:

{
    "freeze_uuid": "pdsRgUtSTymVDWR_HoTGFw"
}

**Table 2** Response parameter
Parameter	Description
freeze_uuid	After an index freezing request is submitted, an asynchronous job will be started. The request returns the asynchronous job ID, which can be used to query the progress of the asynchronous job.

After an index freezing request is submitted, data cannot be written to the index. During the index freezing, query requests are not affected. After the freezing is complete, the index is closed and then opened. During this period, the index cannot be queried, and the cluster may be in the red status for a short time. The index is restored after being opened.

Run the following command to check the freezing task progress:

GET _freeze_low_cost_progress/${freeze_uuid}

**Table 3** Parameter description
Parameter	Description
freeze_uuid	Asynchronous task ID, which is obtained in 4.

Information similar to the following is displayed:

{

  "stage" : "STARTED",
  "shards_stats" : {
    "INIT" : 0,
    "FAILURE" : 0,
    "DONE" : 0,
    "STARTED" : 3,
    "ABORTED" : 0
  },
  "indices" : {
    "data1" : [
      {
        "uuid" : "7OS-G1-tRke2jHZPlckexg",
        "index" : {
          "name" : "data1",
          "index_id" : "4b5PHXJITLaS6AurImfQ9A",
          "shard" : 2
        },
        "start_ms" : 1611972010852,
        "end_ms" : -1,
        "total_time" : "10.5s",
        "total_time_in_millis" : 10505,
        "stage" : "STARTED",
        "failure" : null,
        "size" : {
          "total_bytes" : 3211446689,
          "finished_bytes" : 222491269,
          "percent" : "6.0%"
        },
        "file" : {
          "total_files" : 271,
          "finished_files" : 12,
          "percent" : "4.0%"
        },
        "rate_limit" : {
          "paused_times" : 1,
          "paused_nanos" : 946460970
        }
      },
      {
        "uuid" : "7OS-G1-tRke2jHZPlckexg",
        "index" : {
          "name" : "data1",
          "index_id" : "4b5PHXJITLaS6AurImfQ9A",
          "shard" : 0
        },
        "start_ms" : 1611972010998,
        "end_ms" : -1,
        "total_time" : "10.3s",
        "total_time_in_millis" : 10359,
        "stage" : "STARTED",
        "failure" : null,
        "size" : {
          "total_bytes" : 3221418186,
          "finished_bytes" : 272347118,
          "percent" : "8.0%"
        },
        "file" : {
          "total_files" : 372,
          "finished_files" : 16,
          "percent" : "4.0%"
        },
        "rate_limit" : {
          "paused_times" : 5,
          "paused_nanos" : 8269016764
        }
      },
      {
        "uuid" : "7OS-G1-tRke2jHZPlckexg",
        "index" : {
          "name" : "data1",
          "index_id" : "4b5PHXJITLaS6AurImfQ9A",
          "shard" : 1
        },
        "start_ms" : 1611972011021,
        "end_ms" : -1,
        "total_time" : "10.3s",
        "total_time_in_millis" : 10336,
        "stage" : "STARTED",
        "failure" : null,
        "size" : {
          "total_bytes" : 3220787498,
          "finished_bytes" : 305789614,
          "percent" : "9.0%"
        },
        "file" : {
          "total_files" : 323,
          "finished_files" : 14,
          "percent" : "4.0%"
        },
        "rate_limit" : {
          "paused_times" : 3,
          "paused_nanos" : 6057933087
        }
      }
    ]
  }
}

**Table 4** Response parameters
Parameter	Description
stage	Status. Its value can be: INIT: The instance has just started or is being initialized. FAILURE: failed DONE: complete STARTED: started ABORTED: Canceled. This field is reserved.
shards_stats	Numbers of shards in each state.
indices	Index status details.

**Table 5** Return values of **indices**
Parameter	Description
uuid	UUID of the freezing operation
index	Index and shard information
start_ms	Start time
end_ms	End time. If no end time is specified, the value -1 is displayed.
total_time	Time spent
total_time_in_millis	Time spent, in milliseconds
stage	Status of the current shard.
failure	Failure cause. If no failure occurs, null is displayed.
size.total_bytes	Size of files to be frozen, in bytes
size.finished_bytes	Frozen bytes
size.percent	Percentage of frozen bytes
file.total_bytes	Number of files to be frozen
file.finished_bytes	Number of frozen files
file.percent	Percentage of frozen files
rate_limit.paused_times	Number of times that freezing is suspended due to rate limit
rate_limit.paused_nanos	Duration of freezing task suspension due to rate limit, in nanoseconds

The following parameters are added to a frozen index. For details, see Table 6.

**Table 6** Frozen index parameters
Parameter	Description
index.frozen_low_cost	Whether an index is frozen. The value is true.
index.blocks.write	Whether data writing is denied in a frozen index. The value is true.
index.store.type	Storage type of an index. The value is obs.

After an index is frozen, its data will be cached. Run the following command to check the current cache status: For details about the cache, see Configuring Cache.

GET _frozen_stats
GET _frozen_stats/${node_id}

**Table 7** Parameter description
Parameter	Description
node_id	Node ID, which can be used to obtain the cache status of a node.

Information similar to the following is displayed:

{
  "_nodes" : {
    "total" : 3,
    "successful" : 3,
    "failed" : 0
  },
  "cluster_name" : "css-zzz1",
  "nodes" : {
    "7uwKO38RRoaON37YsXhCYw" : {
      "name" : "css-zzz1-ess-esn-2-1",
      "transport_address" : "10.0.0.247:9300",
      "host" : "10.0.0.247",
      "ip" : "10.0.0.247",
      "block_cache" : {
        "default" : {
          "type" : "memory",
          "block_cache_capacity" : 8192,
          "block_cache_blocksize" : 8192,
          "block_cache_size" : 12,
          "block_cache_hit" : 14,
          "block_cache_miss" : 0,
          "block_cache_eviction" : 0,
          "block_cache_store_fail" : 0
        }
      },
      "obs_stats" : {
        "list" : {
          "obs_list_count" : 17,
          "obs_list_ms" : 265,
          "obs_list_avg_ms" : 15
        },
        "get_meta" : {
          "obs_get_meta_count" : 79,
          "obs_get_meta_ms" : 183,
          "obs_get_meta_avg_ms" : 2
        },
        "get_obj" : {
          "obs_get_obj_count" : 12,
          "obs_get_obj_ms" : 123,
          "obs_get_obj_avg_ms" : 10
        },
        "put_obj" : {
          "obs_put_obj_count" : 12,
          "obs_put_obj_ms" : 2451,
          "obs_put_obj_avg_ms" : 204
        },
        "obs_op_total" : {
          "obs_op_total_ms" : 3022,
          "obs_op_total_count" : 120,
          "obs_op_avg_ms" : 25
        }
      },
      "reader_cache" : {
        "hit_count" : 0,
        "miss_count" : 1,
        "load_success_count" : 1,
        "load_exception_count" : 0,
        "total_load_time" : 291194714,
        "eviction_count" : 0
      }
    },
    "73EDpEqoQES749umJqxOzQ" : {
      "name" : "css-zzz1-ess-esn-3-1",
      "transport_address" : "10.0.0.201:9300",
      "host" : "10.0.0.201",
      "ip" : "10.0.0.201",
      "block_cache" : {
        "default" : {
          "type" : "memory",
          "block_cache_capacity" : 8192,
          "block_cache_blocksize" : 8192,
          "block_cache_size" : 12,
          "block_cache_hit" : 14,
          "block_cache_miss" : 0,
          "block_cache_eviction" : 0,
          "block_cache_store_fail" : 0
        }
      },
      "obs_stats" : {
        "list" : {
          "obs_list_count" : 17,
          "obs_list_ms" : 309,
          "obs_list_avg_ms" : 18
        },
        "get_meta" : {
          "obs_get_meta_count" : 79,
          "obs_get_meta_ms" : 216,
          "obs_get_meta_avg_ms" : 2
        },
        "get_obj" : {
          "obs_get_obj_count" : 12,
          "obs_get_obj_ms" : 140,
          "obs_get_obj_avg_ms" : 11
        },
        "put_obj" : {
          "obs_put_obj_count" : 12,
          "obs_put_obj_ms" : 1081,
          "obs_put_obj_avg_ms" : 90
        },
        "obs_op_total" : {
          "obs_op_total_ms" : 1746,
          "obs_op_total_count" : 120,
          "obs_op_avg_ms" : 14
        }
      },
      "reader_cache" : {
        "hit_count" : 0,
        "miss_count" : 1,
        "load_success_count" : 1,
        "load_exception_count" : 0,
        "total_load_time" : 367179751,
        "eviction_count" : 0
      }
    },
    "EF8WoLCUQbqJl1Pkqo9-OA" : {
      "name" : "css-zzz1-ess-esn-1-1",
      "transport_address" : "10.0.0.18:9300",
      "host" : "10.0.0.18",
      "ip" : "10.0.0.18",
      "block_cache" : {
        "default" : {
          "type" : "memory",
          "block_cache_capacity" : 8192,
          "block_cache_blocksize" : 8192,
          "block_cache_size" : 12,
          "block_cache_hit" : 14,
          "block_cache_miss" : 0,
          "block_cache_eviction" : 0,
          "block_cache_store_fail" : 0
        }
      },
      "obs_stats" : {
        "list" : {
          "obs_list_count" : 17,
          "obs_list_ms" : 220,
          "obs_list_avg_ms" : 12
        },
        "get_meta" : {
          "obs_get_meta_count" : 79,
          "obs_get_meta_ms" : 139,
          "obs_get_meta_avg_ms" : 1
        },
        "get_obj" : {
          "obs_get_obj_count" : 12,
          "obs_get_obj_ms" : 82,
          "obs_get_obj_avg_ms" : 6
        },
        "put_obj" : {
          "obs_put_obj_count" : 12,
          "obs_put_obj_ms" : 879,
          "obs_put_obj_avg_ms" : 73
        },
        "obs_op_total" : {
          "obs_op_total_ms" : 1320,
          "obs_op_total_count" : 120,
          "obs_op_avg_ms" : 11
        }
      },
      "reader_cache" : {
        "hit_count" : 0,
        "miss_count" : 1,
        "load_success_count" : 1,
        "load_exception_count" : 0,
        "total_load_time" : 235706838,
        "eviction_count" : 0
      }
    }
  }
}

Run the following command to reset the cache status:
```
POST _frozen_stats/reset
```
Information similar to the following is displayed:
```
{
  "_nodes" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0
  },
  "cluster_name" : "Es-0325-007_01",
  "nodes" : {
    "mqTdk2YRSPyOSXfesREFSg" : {
      "result" : "ok"
    }
  }
}
```
This command is used to debug performance issues. If you reset the cache status and run this command, you can check the cache command status. You do not need to run this command during service running.
Run the following command to check all the frozen indexes:
```
GET _cat/freeze_indices
```
Information similar to the following is displayed:
```
green open data2 0bNtxWDtRbOSkS4JYaUgMQ 3 0  5 0  7.9kb  7.9kb
green open data3 oYMLvw31QnyasqUNuyP6RA 3 0 51 0 23.5kb 23.5kb
```
The parameters and return values of this command are the same as those of _cat/indices of Elasticsearch.