本篇文章为你整理了Restore a snapshot（）的详细内容，包含有 Restore a snapshot，希望能帮助你了解 Restore a snapshot。

　　IMPORTANT: No additional bug fixes or documentation updates

　　will be released for this version. For the latest information, see the

　　current release documentation.

　　
By default, all data streams and indices in the snapshot are restored, but the cluster state is

　　not restored. Use the indices parameter to restore only specific data streams or indices. This parameter

　　supports multi-target syntax. To include the global cluster state, set

　　include_global_state to true in the restore request body.

　　
Each data stream requires a matching

　　index template. The stream uses this

　　template to create new backing indices.

　　When restoring a data stream, ensure a matching template exists for the stream.

　　You can do this using one of the following methods:

　　
Check for existing templates that match the stream. If no matching template

　　exists, create one.

　　
If no index template matches a data stream, the stream cannot

　　roll over or create new backing indices.

　　
The rename_pattern

　　and rename_replacement options can be also used to rename data streams and indices on restore

　　using regular expression that supports referencing the original text, according to the appendReplacement logic.

　　If you rename a restored data stream, its backing indices are also

　　renamed. For example, if you rename the logs data stream to restored-logs,

　　the backing index .ds-logs-000005 is renamed to .ds-restored-logs-000005.

　　
If you rename a restored stream, ensure an index template matches the new stream

　　name. If no index template matches the stream, it cannot

　　roll over or create new backing indices.

　　
Set include_aliases to false to prevent aliases from being restored together

　　with associated indices

POST /_snapshot/my_backup/snapshot_1/_restore

　　 "indices": "data_stream_1,index_1,index_2",

　　 "ignore_unavailable": true,

　　 "include_global_state": false,

　　 "rename_pattern": "index_(.+)",

　　 "rename_replacement": "restored_index_$1",

　　 "include_aliases": false

　　}

　　
By default, include_global_state is false, meaning the snapshot s

　　cluster state is not restored.

　　If true, the snapshot s persistent settings, index templates, ingest

　　pipelines, and ILM policies are restored into the current cluster. This

　　overwrites any existing cluster settings, templates, pipelines and ILM

　　policies whose names match those in the snapshot.

　　
Regular expression that matches data streams and indices in the snapshot. Supports regular expression constructs.

　　
Renames data streams and indices that match the rename_pattern. $1 is a reference to the first capturing group. In this example, index_1 and index_2 will be renamed as restored_index_1 and restored_index_2.

　　
The restore operation must be performed on a functioning cluster. However, an

　　existing index can be only restored if it s closed and

　　has the same number of shards as the index in the snapshot. The restore

　　operation automatically opens restored indices if they were closed and creates

　　new indices if they didn t exist in the cluster.

　　If a data stream is restored, its backing indices are also restored. The restore

　　operation automatically opens restored backing indices if they were closed.

　　
In addition to entire data streams, you can restore only specific backing

　　indices from a snapshot. However, restored backing indices are not automatically

　　added to any existing data streams. For example, if only the .ds-logs-000003

　　backing index is restored from a snapshot, it is not automatically added to the

　　existing logs data stream.

　　Partial restoreedit

　　By default, the entire restore operation will fail if one or more indices or backing indices participating in the operation don t have

　　snapshots of all shards available. It can occur if some shards failed to snapshot for example. It is still possible to

　　restore such indices by setting partial to true. Please note, that only successfully snapshotted shards will be

　　restored in this case and all missing shards will be recreated empty.

　　Changing index settings during restoreedit

　　Use the index_settings parameter

　　to override index settings during the restore process. For example, the

　　following request will restore the index index_1 without creating any

　　replicas while switching back to the default refresh interval:

POST /_snapshot/my_backup/snapshot_1/_restore

　　 "indices": "index_1",

　　 "ignore_unavailable": true,

　　 "index_settings": {

　　 "index.number_of_replicas": 0

　　 "ignore_index_settings": [

　　 "index.refresh_interval"

　　}

　　
Some settings such as index.number_of_shards cannot be changed during the restore operation.

　　
For data streams, these index settings are applied to the restored backing

　　indices.

　　
The index_settings and ignore_index_settings parameters affect

　　restored backing indices only. New backing indices created for a stream use the index

　　settings specified in the stream s matching

　　index template.

　　If you change index settings during a restore, we recommend you make similar

　　changes in the stream s matching index template. This ensures new backing

　　indices created for the stream use the same index settings.

　　
Restoring to a different clusteredit

　　The information stored in a snapshot is not tied to a particular cluster or a cluster name. Therefore, it s possible to

　　restore a snapshot created from one cluster into another cluster by registering the repository that contains the snapshot in the new cluster and starting the restore process.

　　The topology of the new cluster does not have to match the cluster where the snapshot was created. However, the version of the new cluster must be the same or only one major version newer than the cluster that was used to create the snapshot. For example, you can restore a 5.x snapshot to a 6.x cluster, but not a 5.x snapshot to a 7.x cluster.

　　If the new cluster has a smaller capacity, consider the following changes:

　　
Ensure that the new cluster has enough capacity to store all data streams and indices in the snapshot.

　　
Change the index settings during the restore operation to reduce the

　　number of replicas.

　　
If indices or backing indices in the original cluster were assigned to particular nodes using

　　shard allocation filtering, the same rules will be enforced in the new cluster. If the new cluster does not contain nodes with appropriate attributes that a restored index can be allocated on, the

　　index will not be successfully restored unless these index allocation settings are changed during the restore operation.

　　The restore operation also checks that restored persistent settings are compatible with the current cluster to avoid accidentally

　　restoring incompatible settings. If you need to restore a snapshot with incompatible persistent settings, try restoring it without

　　the global cluster state.

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