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4a4e3d70d5
This commit changes the default out-of-the-box configuration for the number of shards from five to one. We think this will help address a common problem of oversharding. For users with time-based indices that need a different default, this can be managed with index templates. For users with non-time-based indices that find they need to re-shard with the split API in place they no longer need to resort only to reindexing. Since this has the impact of changing the default number of shards used in REST tests, we want to ensure that we still have coverage for issues that could arise from multiple shards. As such, we randomize (rarely) the default number of shards in REST tests to two. This is managed via a global index template. However, some tests check the templates that are in the cluster state during the test. Since this template is randomly there, we need a way for tests to skip adding the template used to set the number of shards to two. For this we add the default_shards feature skip. To avoid having to write our docs in a complicated way because sometimes they might be behind one shard, and sometimes they might be behind two shards we apply the default_shards feature skip to all docs tests. That is, these tests will always run with the default number of shards (one).
87 lines
3.5 KiB
Plaintext
87 lines
3.5 KiB
Plaintext
[[cat-health]]
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== cat health
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`health` is a terse, one-line representation of the same information
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from `/_cluster/health`.
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[source,js]
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--------------------------------------------------
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GET /_cat/health?v
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--------------------------------------------------
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// CONSOLE
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// TEST[s/^/PUT twitter\n{"settings":{"number_of_replicas": 0}}\n/]
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[source,txt]
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--------------------------------------------------
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epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
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1475871424 16:17:04 elasticsearch green 1 1 1 1 0 0 0 0 - 100.0%
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--------------------------------------------------
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// TESTRESPONSE[s/1475871424 16:17:04/\\d+ \\d+:\\d+:\\d+/]
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// TESTRESPONSE[s/elasticsearch/[^ ]+/ s/0 -/\\d+ (-|\\d+(\\.\\d+)?[ms]+)/ _cat]
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It has one option `ts` to disable the timestamping:
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[source,js]
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--------------------------------------------------
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GET /_cat/health?v&ts=false
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--------------------------------------------------
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// CONSOLE
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// TEST[s/^/PUT twitter\n{"settings":{"number_of_replicas": 0}}\n/]
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which looks like:
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[source,txt]
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--------------------------------------------------
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cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
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elasticsearch green 1 1 1 1 0 0 0 0 - 100.0%
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--------------------------------------------------
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// TESTRESPONSE[s/elasticsearch/[^ ]+/ s/0 -/\\d+ (-|\\d+(\\.\\d+)?[ms]+)/ _cat]
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A common use of this command is to verify the health is consistent
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across nodes:
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[source,sh]
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--------------------------------------------------
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% pssh -i -h list.of.cluster.hosts curl -s localhost:9200/_cat/health
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[1] 20:20:52 [SUCCESS] es3.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0 0
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[2] 20:20:52 [SUCCESS] es1.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0 0
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[3] 20:20:52 [SUCCESS] es2.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0 0
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--------------------------------------------------
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// NOTCONSOLE
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A less obvious use is to track recovery of a large cluster over
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time. With enough shards, starting a cluster, or even recovering after
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losing a node, can take time (depending on your network & disk). A way
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to track its progress is by using this command in a delayed loop:
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[source,sh]
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--------------------------------------------------
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% while true; do curl localhost:9200/_cat/health; sleep 120; done
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1384309446 18:24:06 foo red 3 3 20 20 0 0 1812 0
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1384309566 18:26:06 foo yellow 3 3 950 916 0 12 870 0
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1384309686 18:28:06 foo yellow 3 3 1328 916 0 12 492 0
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1384309806 18:30:06 foo green 3 3 1832 916 4 0 0
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^C
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--------------------------------------------------
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// NOTCONSOLE
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In this scenario, we can tell that recovery took roughly four minutes.
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If this were going on for hours, we would be able to watch the
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`UNASSIGNED` shards drop precipitously. If that number remained
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static, we would have an idea that there is a problem.
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[float]
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[[timestamp]]
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=== Why the timestamp?
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You typically are using the `health` command when a cluster is
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malfunctioning. During this period, it's extremely important to
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correlate activities across log files, alerting systems, etc.
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There are two outputs. The `HH:MM:SS` output is simply for quick
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human consumption. The epoch time retains more information, including
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date, and is machine sortable if your recovery spans days.
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