Allow shards of closed indices to be replicated as regular shards #38024
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tlrx
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>enhancement
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:Distributed/Distributed
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Pinging @elastic/es-distributed |
This was referenced Jan 30, 2019
ywelsch
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Jan 31, 2019
server/src/main/java/org/elasticsearch/snapshots/RestoreService.java
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server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataIndexStateService.java
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server/src/main/java/org/elasticsearch/cluster/routing/RoutingTable.java
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server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataIndexStateService.java
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| assert indexMetaData != null || event.isNewCluster() : | ||
| "index " + index + " does not exist in the cluster state, it should either " + | ||
| "have been deleted or the cluster must be new"; | ||
| final AllocatedIndices.IndexRemovalReason reason = | ||
| indexMetaData != null && indexMetaData.getState() == IndexMetaData.State.CLOSE ? CLOSED : NO_LONGER_ASSIGNED; |
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for BWC reasons, I think we will need to keep this.
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I guess you're thinking of the search context releasing?
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Sorry for not being clear here. I was rather thinking about the case where an older-version master has removed the routing table for a closed index (i.e. old-style closed indices). We still need to handle these here.
server/src/main/java/org/elasticsearch/indices/cluster/IndicesClusterStateService.java
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tlrx
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Feb 1, 2019
…xisting indices (#38177) When restoring shards of existing indices, the RestoreService also restores the values of primary terms stored in the snapshot index metadata. The primary terms are not updated and could potentially conflict with current index primary terms if the restored primary terms are lower than the existing ones. This situation is likely to happen with replicated closed indices (because primary terms are increased when the index is transitioning from open to closed state, and the snapshotted primary terms are the one at the time the index was opened) (see #38024) and maybe also with CCR. This commit changes the RestoreService so that it updates the primary terms using the maximum value between the snapshotted values and the existing values. Related to #33888
tlrx
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Feb 1, 2019
…xisting indices (elastic#38177) When restoring shards of existing indices, the RestoreService also restores the values of primary terms stored in the snapshot index metadata. The primary terms are not updated and could potentially conflict with current index primary terms if the restored primary terms are lower than the existing ones. This situation is likely to happen with replicated closed indices (because primary terms are increased when the index is transitioning from open to closed state, and the snapshotted primary terms are the one at the time the index was opened) (see elastic#38024) and maybe also with CCR. This commit changes the RestoreService so that it updates the primary terms using the maximum value between the snapshotted values and the existing values. Backport elastic/elasticsearch@da6269b Related to elastic#33888
tlrx
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Feb 1, 2019
…xisting indices (#38177) When restoring shards of existing indices, the RestoreService also restores the values of primary terms stored in the snapshot index metadata. The primary terms are not updated and could potentially conflict with current index primary terms if the restored primary terms are lower than the existing ones. This situation is likely to happen with replicated closed indices (because primary terms are increased when the index is transitioning from open to closed state, and the snapshotted primary terms are the one at the time the index was opened) (see #38024) and maybe also with CCR. This commit changes the RestoreService so that it updates the primary terms using the maximum value between the snapshotted values and the existing values. Backport da6269b Related to #33888
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Thanks for the review @ywelsch ! I updated the code, can you have another look please? |
ywelsch
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Feb 4, 2019
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Thanks @ywelsch! 🎉 |
tlrx
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Feb 28, 2019
Before this change, closed indexes were simply not replicated. It was therefore possible to close an index and then decommission a data node without knowing that this data node contained shards of the closed index, potentially leading to data loss. Shards of closed indices were not completely taken into account when balancing the shards within the cluster, or automatically replicated through shard copies, and they were not easily movable from node A to node B using APIs like Cluster Reroute without being fully reopened and closed again. This commit changes the logic executed when closing an index, so that its shards are not just removed and forgotten but are instead reinitialized and reallocated on data nodes using an engine implementation which does not allow searching or indexing, which has a low memory overhead (compared with searchable/indexable opened shards) and which allows shards to be recovered from peer or promoted as primaries when needed. This new closing logic is built on top of the new Close Index API introduced in 6.7.0 (#37359). Some pre-closing sanity checks are executed on the shards before closing them, and closing an index on a 8.0 cluster will reinitialize the index shards and therefore impact the cluster health. Some APIs have been adapted to make them work with closed indices: - Cluster Health API - Cluster Reroute API - Cluster Allocation Explain API - Recovery API - Cat Indices - Cat Shards - Cat Health - Cat Recovery This commit contains all the following changes (most recent first): * c6c42a1 Adapt NoOpEngineTests after #39006 * 3f9993d Wait for shards to be active after closing indices (#38854) * 5e7a428 Adapt the Cluster Health API to closed indices (#39364) * 3e61939 Adapt CloseFollowerIndexIT for replicated closed indices (#38767) * 71f5c34 Recover closed indices after a full cluster restart (#39249) * 4db7fd9 Adapt the Recovery API for closed indices (#38421) * 4fd1bb2 Adapt more tests suites to closed indices (#39186) * 0519016 Add replica to primary promotion test for closed indices (#39110) * b756f6c Test the Cluster Shard Allocation Explain API with closed indices (#38631) * c484c66 Remove index routing table of closed indices in mixed versions clusters (#38955) * 00f1828 Mute CloseFollowerIndexIT.testCloseAndReopenFollowerIndex() * e845b0a Do not schedule Refresh/Translog/GlobalCheckpoint tasks for closed indices (#38329) * cf9a015 Adapt testIndexCanChangeCustomDataPath for replicated closed indices (#38327) * b9becdd Adapt testPendingTasks() for replicated closed indices (#38326) * 02cc730 Allow shards of closed indices to be replicated as regular shards (#38024) * e53a9be Fix compilation error in IndexShardIT after merge with master * cae4155 Relax NoOpEngine constraints (#37413) * 54d110b [RCI] Adapt NoOpEngine to latest FrozenEngine changes * c63fd69 [RCI] Add NoOpEngine for closed indices (#33903) Relates to #33888
tlrx
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Mar 1, 2019
…astic#38024) This commit allows shards of indices in CLOSE state to be replicated as normal shards. It changes the MetaDataIndexStateService so that index routing tables of closed indices are kept in cluster state when the index is closed. Index routing tables are modified so that shard routings are reinitialized with the INDEX_CLOSED unassigned information. The IndicesClusterStateService is modified to remove IndexService instances of closed or reopened indices. In combination with the ShardRouting being in INITIALIZING state the shards are recreated on the data nodes to reflect the new state. If the index state is closed, the IndexShard instances will be created using the NoOpEngine as the engine implementation. This commit also mutes two tests that rely on the fact that shard locks are released when an index is closed, which is not the case anymore with replicated closed indices (actually the locks are released but reacquired once the shard is reinitialized after being closed). These tests will be adapted in follow up PRs. Finally, many things will require to be adapted or improved in follow up PRs (see elastic#33888) but this is the first big step towards replicated closed indices. Relates to elastic#33888
tlrx
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Mar 1, 2019
tlrx
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Mar 1, 2019
Backport support for replicating closed indices (#39499) Before this change, closed indexes were simply not replicated. It was therefore possible to close an index and then decommission a data node without knowing that this data node contained shards of the closed index, potentially leading to data loss. Shards of closed indices were not completely taken into account when balancing the shards within the cluster, or automatically replicated through shard copies, and they were not easily movable from node A to node B using APIs like Cluster Reroute without being fully reopened and closed again. This commit changes the logic executed when closing an index, so that its shards are not just removed and forgotten but are instead reinitialized and reallocated on data nodes using an engine implementation which does not allow searching or indexing, which has a low memory overhead (compared with searchable/indexable opened shards) and which allows shards to be recovered from peer or promoted as primaries when needed. This new closing logic is built on top of the new Close Index API introduced in 6.7.0 (#37359). Some pre-closing sanity checks are executed on the shards before closing them, and closing an index on a 8.0 cluster will reinitialize the index shards and therefore impact the cluster health. Some APIs have been adapted to make them work with closed indices: - Cluster Health API - Cluster Reroute API - Cluster Allocation Explain API - Recovery API - Cat Indices - Cat Shards - Cat Health - Cat Recovery This commit contains all the following changes (most recent first): * c6c42a1 Adapt NoOpEngineTests after #39006 * 3f9993d Wait for shards to be active after closing indices (#38854) * 5e7a428 Adapt the Cluster Health API to closed indices (#39364) * 3e61939 Adapt CloseFollowerIndexIT for replicated closed indices (#38767) * 71f5c34 Recover closed indices after a full cluster restart (#39249) * 4db7fd9 Adapt the Recovery API for closed indices (#38421) * 4fd1bb2 Adapt more tests suites to closed indices (#39186) * 0519016 Add replica to primary promotion test for closed indices (#39110) * b756f6c Test the Cluster Shard Allocation Explain API with closed indices (#38631) * c484c66 Remove index routing table of closed indices in mixed versions clusters (#38955) * 00f1828 Mute CloseFollowerIndexIT.testCloseAndReopenFollowerIndex() * e845b0a Do not schedule Refresh/Translog/GlobalCheckpoint tasks for closed indices (#38329) * cf9a015 Adapt testIndexCanChangeCustomDataPath for replicated closed indices (#38327) * b9becdd Adapt testPendingTasks() for replicated closed indices (#38326) * 02cc730 Allow shards of closed indices to be replicated as regular shards (#38024) * e53a9be Fix compilation error in IndexShardIT after merge with master * cae4155 Relax NoOpEngine constraints (#37413) * 54d110b [RCI] Adapt NoOpEngine to latest FrozenEngine changes * c63fd69 [RCI] Add NoOpEngine for closed indices (#33903) Relates to #33888
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Note: this pull request is aimed to be merged in the
replicated-closed-indicesfeature branchThis pull request allows shards of indices in
CLOSEstate to be replicated as normal shards. It changes theMetaDataIndexStateServiceso that index routing tables of closed indices are kept in cluster state when the index is closed. Index routing tables are modified so that shard routings are reinitialized with theINDEX_CLOSEDunassigned information. TheIndicesClusterStateServiceis modified to removeIndexServiceinstances of closed or reopened indices. In combination with theShardRoutingbeing inINITIALIZINGstate the shards are recreated on the data nodes to reflect the new state. If the index state is closed, theIndexShardinstances will be created using theNoOpEngineas the engine implementation.This pull request also modifies the
RestoreServiceso that primary terms are increased when indices are restored from snapshots. This is necessary in order to avoid shards to be restored with primary terms that have a value lower than the current primary term (which is increased when the index is closed).This pull request also mutes two tests that rely on the fact that shard locks are released when an index is closed, which is not the case anymore with replicated closed indices (actually the locks are released but reacquired once the shard is reinitialized after being closed). These tests will be adapted in follow up PRs.
Finally, many things will require to be adapted or improved in follow up PRs (see #33888) but this is the first big step towards replicated closed indices.