97 lines
4.3 KiB
Plaintext
97 lines
4.3 KiB
Plaintext
[[snapshot-restore]]
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= Snapshot and restore
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[partintro]
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--
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// tag::snapshot-intro[]
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A _snapshot_ is a backup taken from a running {es} cluster.
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You can take snapshots of individual indices or of the entire cluster.
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Snapshots can be stored in either local or remote repositories.
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Remote repositories can reside on S3, HDFS, Azure, Google Cloud Storage,
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and other platforms supported by a repository plugin.
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Snapshots are incremental: each snapshot of an index only stores data that
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is not part of an earlier snapshot.
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This enables you to take frequent snapshots with minimal overhead.
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// end::snapshot-intro[]
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// tag::restore-intro[]
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You can restore snapshots to a running cluster with the <<snapshots-restore-snapshot,restore API>>.
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By default, all indices in the snapshot are restored.
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Alternatively, you can restore specific indices or restore the cluster state from a snapshot.
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When restoring indices, you can modify the index name and selected index settings.
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// end::restore-intro[]
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You must <<snapshots-register-repository, register a snapshot repository>>
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before you can <<snapshots-take-snapshot, take snapshots>>.
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You can use <<getting-started-snapshot-lifecycle-management, snapshot lifecycle management>>
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to automatically take and manage snapshots.
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// tag::backup-warning[]
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WARNING: You cannot back up an {es} cluster by simply copying
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the data directories of all of its nodes. {es} may be making changes to
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the contents of its data directories while it is running; copying its data
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directories cannot be expected to capture a consistent picture of their contents.
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If you try to restore a cluster from such a backup, it may fail and report
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corruption and/or missing files. Alternatively, it may appear to have succeeded
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though it silently lost some of its data. The only reliable way to back up a
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cluster is by using the snapshot and restore functionality.
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// end::backup-warning[]
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[float]
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[[snapshot-restore-version-compatibility]]
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=== Version compatibility
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IMPORTANT: Version compatibility refers to the underlying Lucene index
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compatibility. Follow the <<setup-upgrade,Upgrade documentation>>
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when migrating between versions.
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A snapshot contains a copy of the on-disk data structures that make up an
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index. This means that snapshots can only be restored to versions of
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{es} that can read the indices:
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* A snapshot of an index created in 6.x can be restored to 7.x.
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* A snapshot of an index created in 5.x can be restored to 6.x.
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* A snapshot of an index created in 2.x can be restored to 5.x.
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* A snapshot of an index created in 1.x can be restored to 2.x.
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Conversely, snapshots of indices created in 1.x **cannot** be restored to 5.x
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or 6.x, snapshots of indices created in 2.x **cannot** be restored to 6.x
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or 7.x, and snapshots of indices created in 5.x **cannot** be restored to 7.x
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or 8.x.
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We do not recommend restoring snapshots from later {es} versions in earlier
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versions. In some cases, the snapshots cannot be restored. For example, a
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snapshot taken in 7.6.0 cannot be restored to 7.5.0.
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Each snapshot can contain indices created in various versions of {es},
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and when restoring a snapshot it must be possible to restore all of the indices
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into the target cluster. If any indices in a snapshot were created in an
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incompatible version, you will not be able restore the snapshot.
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IMPORTANT: When backing up your data prior to an upgrade, keep in mind that you
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won't be able to restore snapshots after you upgrade if they contain indices
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created in a version that's incompatible with the upgrade version.
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If you end up in a situation where you need to restore a snapshot of an index
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that is incompatible with the version of the cluster you are currently running,
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you can restore it on the latest compatible version and use
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<<reindex-from-remote,reindex-from-remote>> to rebuild the index on the current
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version. Reindexing from remote is only possible if the original index has
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source enabled. Retrieving and reindexing the data can take significantly
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longer than simply restoring a snapshot. If you have a large amount of data, we
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recommend testing the reindex from remote process with a subset of your data to
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understand the time requirements before proceeding.
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--
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include::register-repository.asciidoc[]
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include::take-snapshot.asciidoc[]
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include::restore-snapshot.asciidoc[]
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include::monitor-snapshot-restore.asciidoc[]
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include::../slm/index.asciidoc[]
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