124 lines
4.2 KiB
Plaintext
124 lines
4.2 KiB
Plaintext
[[shard-tool]]
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== elasticsearch-shard
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In some cases the Lucene index or translog of a shard copy can become corrupted.
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The `elasticsearch-shard` command enables you to remove corrupted parts of the
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shard if a good copy of the shard cannot be recovered automatically or restored
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from backup.
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[WARNING]
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You will lose the corrupted data when you run `elasticsearch-shard`. This tool
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should only be used as a last resort if there is no way to recover from another
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copy of the shard or restore a snapshot.
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[discrete]
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=== Synopsis
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[source,shell]
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--------------------------------------------------
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bin/elasticsearch-shard remove-corrupted-data
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([--index <Index>] [--shard-id <ShardId>] | [--dir <IndexPath>])
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[--truncate-clean-translog]
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[-E <KeyValuePair>]
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[-h, --help] ([-s, --silent] | [-v, --verbose])
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--------------------------------------------------
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[discrete]
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=== Description
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When {es} detects that a shard's data is corrupted, it fails that shard copy and
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refuses to use it. Under normal conditions, the shard is automatically recovered
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from another copy. If no good copy of the shard is available and you cannot
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restore one from a snapshot, you can use `elasticsearch-shard` to remove the
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corrupted data and restore access to any remaining data in unaffected segments.
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[WARNING]
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Stop Elasticsearch before running `elasticsearch-shard`.
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To remove corrupted shard data use the `remove-corrupted-data` subcommand.
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There are two ways to specify the path:
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* Specify the index name and shard name with the `--index` and `--shard-id`
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options.
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* Use the `--dir` option to specify the full path to the corrupted index or
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translog files.
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[discrete]
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==== Removing corrupted data
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`elasticsearch-shard` analyses the shard copy and provides an overview of the
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corruption found. To proceed you must then confirm that you want to remove the
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corrupted data.
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[WARNING]
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Back up your data before running `elasticsearch-shard`. This is a destructive
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operation that removes corrupted data from the shard.
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[source,txt]
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--------------------------------------------------
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$ bin/elasticsearch-shard remove-corrupted-data --index twitter --shard-id 0
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WARNING: Elasticsearch MUST be stopped before running this tool.
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Please make a complete backup of your index before using this tool.
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Opening Lucene index at /var/lib/elasticsearchdata/nodes/0/indices/P45vf_YQRhqjfwLMUvSqDw/0/index/
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>> Lucene index is corrupted at /var/lib/elasticsearchdata/nodes/0/indices/P45vf_YQRhqjfwLMUvSqDw/0/index/
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Opening translog at /var/lib/elasticsearchdata/nodes/0/indices/P45vf_YQRhqjfwLMUvSqDw/0/translog/
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>> Translog is clean at /var/lib/elasticsearchdata/nodes/0/indices/P45vf_YQRhqjfwLMUvSqDw/0/translog/
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Corrupted Lucene index segments found - 32 documents will be lost.
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WARNING: YOU WILL LOSE DATA.
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Continue and remove docs from the index ? Y
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WARNING: 1 broken segments (containing 32 documents) detected
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Took 0.056 sec total.
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Writing...
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OK
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Wrote new segments file "segments_c"
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Marking index with the new history uuid : 0pIBd9VTSOeMfzYT6p0AsA
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Changing allocation id V8QXk-QXSZinZMT-NvEq4w to tjm9Ve6uTBewVFAlfUMWjA
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You should run the following command to allocate this shard:
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POST /_cluster/reroute
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{
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"commands" : [
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{
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"allocate_stale_primary" : {
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"index" : "index42",
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"shard" : 0,
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"node" : "II47uXW2QvqzHBnMcl2o_Q",
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"accept_data_loss" : false
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}
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}
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]
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}
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You must accept the possibility of data loss by changing the `accept_data_loss` parameter to `true`.
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Deleted corrupt marker corrupted_FzTSBSuxT7i3Tls_TgwEag from /var/lib/elasticsearchdata/nodes/0/indices/P45vf_YQRhqjfwLMUvSqDw/0/index/
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--------------------------------------------------
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When you use `elasticsearch-shard` to drop the corrupted data, the shard's
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allocation ID changes. After restarting the node, you must use the
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<<cluster-reroute,cluster reroute API>> to tell Elasticsearch to use the new ID.
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The `elasticsearch-shard` command shows the request that you need to submit.
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You can also use the `-h` option to get a list of all options and parameters
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that the `elasticsearch-shard` tool supports.
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Finally, you can use the `--truncate-clean-translog` option to truncate the
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shard's translog even if it does not appear to be corrupt.
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