68 lines
2.3 KiB
Plaintext
68 lines
2.3 KiB
Plaintext
[role="xpack"]
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[testenv="platinum"]
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[[ccr-upgrading]]
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=== Upgrading clusters using {ccr}
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++++
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<titleabbrev>Upgrading clusters</titleabbrev>
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++++
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Clusters that are actively using {ccr} require a careful approach to upgrades.
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The following conditions could cause index following to fail during rolling
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upgrades:
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* Clusters that have not yet been upgraded will reject new index settings or
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mapping types that are replicated from an upgraded cluster.
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* Nodes in a cluster that has not been upgraded will reject index files from a
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node in an upgraded cluster when index following tries to fall back to
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file-based recovery. This limitation is due to Lucene not being forward
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compatible.
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The approach to running a rolling upgrade on clusters where {ccr} is
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enabled differs based on uni-directional and bi-directional index following.
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[[ccr-uni-directional-upgrade]]
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==== Uni-directional index following
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In a uni-directional configuration, one cluster contains only
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leader indices, and the other cluster contains only follower indices that
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replicate the leader indices.
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In this strategy, the cluster with follower indices should be upgraded
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first and the cluster with leader indices should be upgraded last.
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Upgrading the clusters in this order ensures that index following can continue
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during the upgrade without downtime.
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You can also use this strategy to upgrade a
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<<ccr-chained-replication,replication chain>>. Start by upgrading clusters at
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the end of the chain and working your way back to the cluster that contains the
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leader indices.
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For example, consider a configuration where Cluster A contains all leader
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indices. Cluster B follows indices in Cluster A, and Cluster C follows indices
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in Cluster B.
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--
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Cluster A
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^--Cluster B
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^--Cluster C
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--
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In this configuration, upgrade the clusters in the following order:
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. Cluster C
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. Cluster B
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. Cluster A
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[[ccr-bi-directional-upgrade]]
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==== Bi-directional index following
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In a bi-directional configuration, each cluster contains both leader and
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follower indices.
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When upgrading clusters in this configuration,
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<<ccr-pause-replication,pause all index following>> and
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<<ccr-auto-follow-pause,pause auto-follow patterns>> prior to
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upgrading both clusters.
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After upgrading both clusters, resume index following and resume replication
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of auto-follow patterns.
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