30 lines
1.6 KiB
Plaintext
30 lines
1.6 KiB
Plaintext
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[role="xpack"]
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[testenv="platinum"]
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[[remote-recovery]]
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== Remote recovery
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When you create a follower index, you cannot use it until it is fully initialized.
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The _remote recovery_ process builds a new copy of a shard on a follower node by
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copying data from the primary shard in the leader cluster. {es} uses this remote
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recovery process to bootstrap a follower index using the data from the leader index.
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This process provides the follower with a copy of the current state of the leader index,
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even if a complete history of changes is not available on the leader due to Lucene
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segment merging.
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Remote recovery is a network intensive process that transfers all of the Lucene
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segment files from the leader cluster to the follower cluster. The follower
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requests that a recovery session be initiated on the primary shard in the leader
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cluster. The follower then requests file chunks concurrently from the leader. By
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default, the process concurrently requests `5` large `1mb` file chunks. This default
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behavior is designed to support leader and follower clusters with high network latency
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between them.
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There are dynamic settings that you can use to rate-limit the transmitted data
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and manage the resources consumed by remote recoveries. See
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{ref}/ccr-settings.html[{ccr-cap} settings].
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You can obtain information about an in-progress remote recovery by using the
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{ref}/cat-recovery.html[recovery API] on the follower cluster. Remote recoveries
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are implemented using the {ref}/modules-snapshots.html[snapshot and restore] infrastructure. This means that on-going remote recoveries are labelled as type
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`snapshot` in the recovery API.
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